UNIVERSITY    OF    CALIFORNIA 

COLLEGE    OF    AGRICULTURE 
AGRICULTURAL   EXPERIMENT  STATION 

CIRCULAR  No.  238 

April,  1922 

THE  APRICOT  IN  CALIFORNIA 

By  W.  L.  HOWARD 


The  number  of  apricot  trees  in  California  in  1920,  as  reported  by 
county  assessors,*  amounted  to  3,339,716  bearing  and  1,325,300  non- 
bearing,  or  a  total  of  4,665,016  trees  young  and  old.  Counting  seventy- 
five  trees  to  the  acre,  this  would  amount  to  62,200  acres.  In  April,  1921, 
the  Prune  and  Apricot  Growers'  Association  estimated  the  total  com- 
mercial acreage  in  the  state  to  be  55,365  acres,  but  these  figures  did  not 
include  home  orchards  or  small  plantings  in  places  remote  from  orchard 
centers.  The  actual  cash  returns  to  the  growers  for  apricots  sold  for 
the  year  1919  (175,000  tons),  amounted  to  $14,000,000  and  for  1920 
(115,500  tons),  to  $9, 775,000. f  These  figures  are  based  on  an  average 
price  of  $80.00  per  ton  in  1919  and  $85.00  in  1920  for  fruit  of  all 
grades.  That  the  estimates  are  conservative  is  evidenced  by  the  fact 
that  in  1920  the  canneries,  which  used  the  bulk  of  the  crop,  paid  from 
$100.00  to  $110.00  a  ton  for  fruit  as  small  as  fourteen  and  even  sixteen 
to  the  pound. 

Apricots  are  grown  in  Oregon,  Washington,  Idaho,  Utah,  Colorado, 
Arizona,  New  Mexico,  Kansas,  and  even  New  York.  No  state  but 
California  produces  them  commercially  in  sufficiently  large  quantities 
to  affect  prices  in  the  principal  markets  of  the  country.  The  U.  S. 
Census  of  1910  reported  that  96.4  per  cent  of  all  the  apricots  grown 
in  the  United  States  were  produced  in  California.  Apricots  are 
profitable  only  in  regions  where  spring  frosts  do  not  kill  the  buds, 
flowers  or  young  fruit,  and  where  there  is  freedom  from  summer  rains, 
which  favor  the  development  of  brown  rot  at  ripening  time.  The 
chief  limiting  factor  is  the  frost  hazard. 

The  advent  of  numerous  canneries  handling  apricots,  coupled  with 
a  strong  fresh-fruit  cooperative  association  and  the  high  prices  pre- 
vailing in  1919  and  1920,  greatly  stimulated  the  planting  of  apricot 
trees  all  over  the  state.  The  planting  was  particularly  heavy  in  the 
Santa  Clara  Valley,  the  Aromas  section  of  Monterey  County,  and  on 

*  Report  of  California  State  Board  of  Equalization  for  1919-1920. 
t  California  Crop   Report,   1920,  Appendix   to   Monthly  Bulletin,   California 
Department  of  Agriculture,  December,  1920. 


J  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

the  rolling  lands  or  so-called  "foothills"  surrounding  the  Pajaro 
Valley  in  Santa  Cruz  County.  Southern  California,  especially  River- 
side  and  Los  Angeles  counties,  shows  a  large  increase  in  acreage  of  this 
fruit. 

Seedling  apricots  were  grown  in  California  as  early  as  1792  at  the 
Santa  Clara  Mission.  Named  varieties,  introduced  from  Europe,  were 
first  planted  by  American  settlers  some  time  previous  to  1850.  Apricots 
are  grown  for  the  fresh-fruit  market,  for  canning,  and  for  drying.  The 
early  fruit  for  eastern  shipment  is  produced  chiefly  in  the  Imperial 
Valley,  near  Vacaville,  and  at  Winters  in  the  Sacramento  Valley. 
Later  in  the  season,  apricots  as  fresh  fruit  are  shipped  from  the  Sacra- 
mento River  region,  and  also  from  the  San  Joaquin  and  Santa  Clara 
valleys.  Apricots  for  canning  are  produced  mainly  in  the  coastal 
valleys  and  the  San  Francisco  Bay  region,  and  for  drying  purposes, 
in  the  San  Joaquin,  Sacramento,  and  other  interior  valleys. 

The  following  summary  in  Table  I  will  give  a  good  general  idea  of 
the  quantities  of  apricots  marketed  fresh,  dried,  and  in  cans  for  the 
years  1915-1920. 

TABLE  I 

Summary  of  Apricots  Marketed  in  California  for  the  Years 

1915  to  1920,  Inclusive 

(From  California  Fruit  News) 

Canned,  Dried,  Fresh, 

Date  cases  tons  cars 

1915  981,190      19,500      329.25 

1916  1,327,770  11,000  289.5 

1917  2,356,553  15,500  403.0 

1918  2,233,314  15,000  440.75 

1919  4,395,204  15,500  419.5 

1920  3.312,020  *10,000  312.0 

The  major  portion  of  the  early  fresh  fruit  sold  went  to  the  eastern 
markets.  "With  improved  methods  of  packing  that  have  come  under  the 
recent  fruit  standardization  laws,  it  is  not  probable  that  the  fresh -fruit 
markets  of  the  east  wrill  ever  become  overstocked,  because  the  areas 
where  early  apricots  can  be  successfully  grown  are  relatively  limited. 
Beginning  about  the  year  1916,  the  demands  of  the  canneries  have 
steadily  reduced  the  amounts  of  apricots  dried  annually.  In  the  coastal 
region  and  the  districts  adjacent  to  San  Francisco  Bay,  the  leading 
variety,  the  Blenheim,  is  grown  almost  exclusively  for  canning,  only 
the  lower  grades  being  dried.  In  the  interior  valleys  even  the  Royal, 
the  premier  drying  variety,  has  been  sent  to  the  canneries  in  large 
quantities  for  the  past  four  or  five  years. 

*  1920  figures  not  final. 


Circular  238]  THE  apricot  in  CALIFORNIA 


APRICOT  DISTRICTS 
Apricots  were  reported  as  growing  in  all  but  seven  of  the  fifty-eight 
counties  of  the  state  in  1920.  One  of  these  counties  is  the  city  of  San 
Francisco,  and  the  other  six  are  in  the  high  Sierras,  where  the  altitude 
makes  the  spring  frost  hazard  too  great  for  such  an  early  blooming 
fruit.  Table  II  shows  the  number  of  bearing  and  non-bearing  trees  in 
each  of  the  counties  in  the  spring  of  1920,  and  also  the  total  number 
in  1909. 

TABLE  II 

Number  of  Bearing  and  Non-bearing  Apricot  Trees  in  the  Various 

Counties  of  California  in  1920.    Also  Total  Number  Bearing 

and  Non-bearing  in  1909 

(1920  statistics  from  Rept.  Cal.  State  Board  Equalization  for  1919-20; 
1909  figures  from  U.  S.  Census  for  1910) 

Bearing,  Non-bearing,       Total  No.  Total  No. 

County  1920  1920  Trees,  1920        Trees,  1909 

Alameda  242,600  3,000  245,600  270,461 

Alpine  6            .             6  7 

Amador  1,365  60  1,425  1,197 

Butte  3,060  4,230  7,290  9,900 

Calaveras   2,000  100  2,100  672 

Colusa  4,000  6,000  10,000  4,420 

Contra  Costa  49,000  3,000  52,000  38,812 

Del  Norte  

El  Dorado  750             750  503 

Fresno  10,480            10,480  186,823 

Glenn  2,000  4,000  6,000  6,830 

Humboldt 250  300  550  235 

Imperial    7,580  4,260  11,840  1,922 

Inyo  342 

Kern 260  275  535  33,573 

Kings  182,900  79,100  262,000  124,007 

Lake  2,000  150  2,150  1,463 

Lassen  400  400  800  70 

Los  Angeles  65,636  46,773  112,409  122,769 

Madera  15,638  5,549  21,187  9,408 

Marin    2,000  500  2,500  1,689 

Mariposa 200            200  233 

Mendocino   4,220  300  4,520  187 

Merced    18,000  33,000  51,000  7,381 

Modoc  775  280  1,055  652 

Mono  6 

Monterey    27,700  27,500  55,200  27,996 

Napa   43,060  21,148  64,208  16,953 

Nevada  115            115  193 

Orange 60,000            60,000  129,352 


4  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

Number  of  Bearing  and  Non-bearing  Apricot  Trees  by  Counties — (Continued) 

County  1920  1920  Trees,  1920        Trees,  1909 

Bearing,  Non-bearing,       Total  No.  Total  No. 

Placer   8,200  12,110  20,310  4,09'2 

Plumas    18 

Riverside    455,500  412,500  868,000  83,069 

Sacramento 30,000  2,500  32,500  10,480 

San  Benito  200,750  150,625  351,375  61,694 

San  Bernardino  119,000  75,100  194,100  111,125 

San  Diego 11,280  2,150  13,430  20,858 

San  Francisco  

San  Joaquin 70,748  26,974  97,722  57,007 

San  Luis  Obispo  50,000  38,900  88,900  20,123 

San  Mateo  9,000            9,000  3,694 

Santa  Barbara 11,050            31,050  15,512 

Santa  Clara  627,500  44,400  671,900  783,585 

Santa  Cruz  73,220  19,807  93,027  63,021 

Shasta  1,000            1,000  839 

Sierra 

Siskiyou 366 

Solano  246,100            246,100  310,262 

Sonoma  31,650  31,740  63,390  9,087 

Stanislaus  48,900  34,800  83,700  20,451 

Sutter   1,239  44  1,283  5,986 

Tehama  38,000            38,000  30,446 

Trinity 170  320  490  41 

Tulare  21,000 21,000  48,834 

Tuolumne  250  127  377  162 

Ventura 417,814  243,118  660,932  219,836 

Yolo  121,200            121,200  117,228 

Yuba   140  50  190  1,481 

From  the  above  table  it  is  learned  that  Riverside  County  has  the 
greatest  total  number  of  trees,  868,000,  but  Santa  Clara  has  the  greatest 
number  in  bearing,  627,500.  Santa  Clara  County  ranks  second  in  total 
number  of  trees  and  Ventura  third.  Ventura  also  holds  third  place 
for  the  number  of  trees  in  bearing.  By  far  the  greatest  increase  in 
any  one  county  in  eleven  years  has  been  in  Riverside  County,  which 
moved  from  eleventh  place  in  1909  to  first  place  in  1920. 

While  apricots  grow  best  in  the  deep,  moist  valley  soils,  they  are 
found  in  abundance  along  the  foothills  of  all  our  mountain  ranges 
where  there  is  sufficient  moisture  to  support  growth.  Although  the 
apricot  seems  to  do  best  in  gravelly  or  sandy  soils,  it  does  well  where 
there  is  a  high  percentage  of  clay,  and  even  in  stiff  adobe.  The  apricot, 
on  its  own  roots  at  least,  will  not  tolerate  a  waterlogged  soil,  but  on 
myrobalan  root  it  is  adapted  to  places  where  the  prune  might  do  well, 
but  where  the  peach  or  cherry  would  not  survive. 


Circular  238]  THe  apricot  in  California  5 

With  the  exception  of  the  almond  and  some  Japanese  plums,  the 
apricot  is  our  earliest  blooming  deciduous  fruit  tree.  It  is  therefore 
restricted  to  districts  comparatively  free  from  spring  frosts.  Observa- 
tion has  shown  that  because  of  the  tenderness  of  the  flower  buds  this 
fruit  is  rarely  profitable  much  above  the  1200-foot  level,  although  the 
tree  itself  is  hardy  up  to  elevations  of  4000  feet. 

One  feature  of  the  apricot's  popularity  has  been  its  habit  of  early 
bearing.  Properly  pruned,  it  will  produce,  during  the  third  year  in 
the  orchard,  from  1500  to  2000  pounds  per  acre,  green  weight,  the 
fourth  year  from  two  to  three  tons,  and  the  fifth  year  between  five  and 
six  tons.  It  is  true,  such  yields  are  much  above  the  average,  but  they 
are  by  no  means  impossible  of  attainment. 

The  apricot  is  not  looked  upon  as  a  long-lived  tree,  although  it 
usually  outlives  the  peach,  Japanese  plum,  and  generally  the  cherry. 
There  are,  however,  many  small  vigorous  orchards  of  apricots  in  the 
state  that  are  forty  to  fifty  years  old.  The  prune  and  European  type 
of  plum  will  scarcely  live  longer.  The  almond,  apple  and  pear,  in  the 
order  named,  will  perhaps  outlive  the  apricot,  prune  and  cherry.  In 
congenial  soil,  the  pear  will  head  the  list  for  longevity.  Under  neglect, 
the  wood  of  the  apricot  soon  becomes  brittle  and  breaks  easily,  and 
organisms  of  decay  admitted  through  wounds  soon  wreck  the  trees. 
An  apricot  orchard  that  is  irrigated  twice  each  year  after  coming  into 
bearing  should  produce  satisfactorily  for  forty  to  fifty  years,  while 
one  that  is  not  properly  provided  with  soil  moisture  can  scarcely  be 
expected  to  remain  profitable  longer  than  twenty-five  to  thirty-five 
years. 

PLANTING  THE  OECHARD 

Apricot  trees  are  usually  planted  24  feet  apart,  in  squares,  but  the 
tendency  is  to  give  them  more  room.  On  deep  soil,  especially  if 
irrigated  regularly,  a  distance  of  25  feet  or  even  26  feet  each  way  is 
better.  With  the  so-called  "long"  system  of  pruning  coming  into 
general  use,  trees  will  need  more  room  than  ever  before.  Under  this 
system  they  do  not  grow  very  tall,  but  have  a  much  greater  spread  than 
under  the  old  plan  of  annual  heading  back  of  all  new  growth.  A  very 
good  arrangement  would  be  to  set  the  trees  24  feet  in  one  direction 
and  26  feet  in  the  other.  This  would  give  better  room  in  the  direction 
in  which  the  principal  orchard  hauling  has  to  be  done.    When  planted 

24  x  24  feet,  there  are  75  trees  to  the  acre,  and  70  trees  when  set  either 

25  x  25  or  24  x  26  feet.     On  deep,  moist  soils,  Moorparks  and  perhaps 
Royals  should  be  set  26  to  30  feet  each  way. 


6  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

It  does  not  pay  to  crowd  the  trees.  A  grower  in  the  Santa  Clara 
Valley  cut  out  every  alternate  row  in  his  apricot  orchard,  with  the  inten- 
tion of  replanting  with  another  variety.  After  delaying  the  replanting 
for  three  years,  he  discovered  that  with  the  forty-five  trees  per  acre 
remaining,  the  orchard  was  producing  the  same  tonnage  as  when  there 
were  ninety  trees  per  acre.  He  claims  to  have  reduced  his  orchard 
expenses  fully  75  per  cent,  and  sums  up  by  saying,  "Why  should  I 
prune,  spray  and  cultivate  two  trees  when  one  will  give  me  the  same 
income  ? "  Of  course,  these  trees  were  much  too  thickly  planted  in  the 
first  place,  which  accounts  for  the  marked  increase  in  yield  per  tree 
when  thinned  out. 

In  laying  out  an  orchard  for  planting,  it  is  a  good  plan  to  make  use 
of  a  surveyor's  transit  in  establishing  the  main  guide  stakes  on  two 
sides  of  the  field.  It  is  a  great  satisfaction  to  have  straight  rows. 
Also,  cultivation  is  greatly  facilitated  if  there  are  no  trees  out  of  line. 
A  stake  should  be  set  where  each  tree  is  to  be  planted.  These  stakes 
may  be  set  by  the  aid  of  a  long  wire  or  surveyors  chain  stretched  across 
the  field  and  having  markers  corresponding  to  the  width  of  the  rows, 
or  by  "  sighting  "  across  the  field  in  two  directions.  The  latter  method 
requires  three  men,  two  to  do  the  "sighting,"  one  in  each  direction, 
and  one  to  set  the  stakes.  A  steel  tape  line,  preferably  100  feet  long, 
is  a  very  important  piece  of  equipment  in  laying  out  an  orchard. 

The  holes  should  be  dug  just  deep  enough  and  wide  enough  to 
contain  the  roots  without  crowding,  after  they  have  been  properly 
trimmed.  The  actual  size  of  the  holes  will  be  determined  by  the  size 
of  the  average  root  system  of  the  trees  to  be  planted.  As  a  rule,  the 
ordinary  one-year-old  tree,  4  to  5  feet  high,  will  require  a  hole  about 
14  inches  in  diameter.  Large  holes,  except  in  the  case  of  replants 
among  old  trees,  are  unnecessary,  provided  the  land  has  been  properly 
prepared  in  advance  by  deep  plowing  and  harrowing. 

Before  starting  to  dig  the  holes,  a  planting  board  may  be  used  by 
setting  two  guide  stakes,  which  serve  to  locate  each  tree  at  the  exact 
place  where  it  should  be  set.  A  convenient  planting  board  may  be 
made  from  a  piece  of  plank,  four  feet  long,  four  or  five  inches  wide, 
and  an  inch  thick.  Saw  a  notch  two  inches  deep  exactly  in  the  center 
at  each  end  and  a  similar  notch  on  one  edge  exactly  in  the  middle  of 
the  board.  Place  a  conspicuous  mark  on  one  side  of  the  board,  and 
always  keep  that  side  up  when  in  use.  Place  the  board  on  the  ground 
with  the  tree  stake  in  the  middle  notch.  Then  drive  a  small  stake  in 
each  of  the  end  notches.  Remove  the  board,  pull  up  the  tree  stake 
and  dig  the  hole.    Two  men  and  a  boy  constitute  a  planting  crew.    The 


Circular  238] 


THE    APRICOT    IN    CALIFORNIA 


boy  distributes  the  trees  to  the  planters  as  needed.  Only  a  small  bundle 
should  be  carried  at  a  time,  and  these  kept  carefully  covered  with 
wet  burlap  until  all  are  dropped  in  the  holes.  In  planting,  one  man 
uses  the  shovel  and  the  other  does  most  of  the  actual  planting.  With 
the  board  in  place,  the  tree  is  held  in  the  center  notch  in  an  upright 
position.  Care  must  be  exercised  to  see  that  it  is  planted  at  exactly 
the  right  depth.     Plant  as  nearly  as  possible  at  the  same  depth  as  it 


Fig.  1. — Trees  for  planting  should  have  the  small  fibrous  roots  removed 
and  the  main  roots  shortened  to  about  six  inches. 


stood  in  the  nursery.  In  heavy  soils  deep  planting  may  kill  the  trees 
or  cause  them  to  make  a  very  poor  growth.  Probably  more  young  trees 
are  destroyed  by  deep  planting  than  by  all  other  causes  combined. 
Such  trees  may  struggle  along  for  two  or  three  years  before  actually 
dying,  and  in  a  few  instances  they  may  recover  if  they  are  able  to 
form  a  new  root  system  above  the  old  one. 

Before  placing  the  tree  in  the  hole,  the  roots  should  be  shortened 
to  a  length  of  about  six  inches  on  all  sides  (fig.  1).  All  fibrous  roots 
less  than  an  eighth  or  a  quarter  of  an  inch  in  diameter  may  be  removed 
entirely.    As  trees  are  ordinarily  handled  between  the  nursery  and  the 


8  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

orchard,  these  fine  roots  make  it  difficult  to  pack  the  soil  in  contact  with 
the  main  roots.  A  knife  is  much  more  convenient  than  shears  for 
trimming  the  roots.  All  broken  or  badly  mangled  roots  should  be  cut 
back  to  firm  wood. 

There  is  a  tradition  in  some  quarters  that  the  "bud"  or  place 
where  the  seedling  was  cut  off  should  be  buried.  If  this  were  always 
done,  many  high-budded  trees  would  be  planted  too  deep.  Others  say 
the  "bud,"  if  left  above  ground,  should  always  be  set  toward  the  pre- 
vailing wind  to  prevent  breaking  off.  This  practice  is  also  unnecessary, 
as  the  point  of  union  between  bud  and  stock  on  a  year-old  tree  is 
strong  enough  to  stand  up  against  any  wind  pressure  to  which  it  is 
likely  to  be  subjected.  If  the  union  is  weak  on  account  of  an  uncon- 
genial root  stock,  the  tree  would  soon  break  off  anyway. 

The  main  thing  is  to  see  that  the  top  of  the  tree  above  the  board 
stands  in  a  perpendicular  position  and  lines  up  with  the  other  trees  in 
the  row.  Sometimes  the  hole  will  be  noticed  at  a  glance  to  be  either  too 
deep  or  too  shallow.  It  is  the  business  of  the  man  with  the  shovel  to 
quickly  remedy  either  defect.  The  first  few  shovels  of  earth  should  be 
fine,  and  the  planter,  especially  if  he  is  a  beginner,  should  get  down 
on  his  knees  and,  holding  the  tree  firmly  in  place  with  one  hand, 
distribute  the  soil  over  the  roots  with  the  other.  The  roots  should  be 
spread  out  in  all  directions  and  more  soil  spread  over  them.  When 
the  first  few  roots  are  covered,  the  soil  may  be  firmed  with  the  foot. 
Ram  the  soil  in  tight — under  the  roots  as  well  as  over  them,  so  that  all 
air  spaces  in  the  crotches  are  well  filled. 

When  the  tree  is  firmly  anchored,  remove  the  board  and  continue 
to  tramp  the  earth  with  both  feet  until  the  hole  is  nearly  filled.  Both 
the  heel  and  toe  are  used  in  ramming  the  soil  firmly  around  the  roots 
and  into  the  crotches.  If  the  soil  is  in  good  condition  for  planting, 
there  is  no  danger  of  packing  too  much.  Just  before  finishing,  if  the 
tree  is  noticed  to  be  slightly  out  of  line,  it  may  be  straightened  by 
ramming  with  the  heel  on  one  side.  A  tree  may  be  easily  crowded 
over  an  inch  or  two  in  this  way.  Do  not  tramp  the  last  inch  of  soil,  as 
it  is  always  well  to  leave  a  fine  surface  mulch  about  each  tree.  When 
the  planting  job  is  completed,  the  ground  about  the  tree  should  be 
level.  If  the  soil  is  rather  dry,  it  is  well  to  leave  a  basin  a  foot  in 
diameter  for  the  purpose  of  pouring  in  two  or  three  gallons  of  water. 
A  properly  planted  tree  cannot  be  pulled  out  of  the  ground  with  one 
hand  by  a  man  of  ordinary  strength. 

It  is  advisable  to  plant  apricot  trees  in  California  as  early  in  the 
winter  as  the  soil  has  been  well  moistened  by  rains.     Usually  the 


Circular  238]  the  apricot  in  California  9 

nursery  stock  cannot  be  dug  until  after  the  late  fall  rains  come.  Plant- 
ing should  preferably  be  done  in  the  month  of  January.  At  this  time 
the  leaves  have  all  dropped  off  naturally,  and  the  wood  is  firm  and 
well  matured. 

It  is  well  to  order  nursery  stock  early  in  the  fall  or  even  in  late 
summer,  stipulating  the  grade  desired  and  that  delivery  shall  be  made 
as  early  in  January  as  possible.  Nurserymen  usually  grade  trees 
according  to  height,  although  diameter  measurement  an  inch  or  two 
above  the  bud  would  be  a  better  way.  Commonly  trees  are  graded  into 
three  sizes,  2  to  3  feet,  3  to  4  feet,  and  5  to  6  feet,  but  when  there  is 
a  shortage  of  stock,  a  1  to  2  foot  size  is  often  quoted.  Sometimes  tall- 
growing  trees  like  prunes,  pears  and  walnuts  are  offered  in  6  to  8  foot 
sizes.  Other  things  being  equal,  a  medium-sized  apricot  tree  is  to  be 
preferred,  say  4  to  5  feet,  or  calipering  one-half  inch  to  five-eighths 
inch.  Eastern  and  northern  nurseries  are  apt  to  sell  by  caliper  meas- 
urement, while  western  nurseries  almost  universally  quote  by  height. 
A  well-grown,  stocky  apricot  tree  three  feet  high  should  be  very  satis- 
factory, but  if  trees  have  been  crowded  in  the  nursery  row,  the  four- 
foot  size  is  better.  There  is  usually  a  difference  of  about  ten  dollars 
per  hundred  between  the  3  to  4,  4  to  5.  and  5  to  6  foot  sizes. 

When  trees  are  received  from  the  nursery,  they  should  always  be 
unpacked  at  once  and  heeled-in  where  the  soil  is  moist.  The  heeling-in 
process  consists  of  laying  the  roots  in  a  trench,  leaning  the  trees  at  an 
angle  of  45  degrees,  with  tops  pointing  toward  the  south,  and  covering 
with  earth  a  foot  or  eighteen  inches  deeper  than  they  are  to  be  planted. 
This  deep  covering  will  not  injure  them  while  dormant.  The  trees 
should  be  well  spread  out  so  that  the  moist  soil  can  come  in  contact 
with  all  the  roots.  Nurseries  always  pack  the  trees  so  they  will  carry 
safely  for  the  distance  they  have  to  be  shipped.  They  should  not  be 
permitted  to  dry  out  after  being  received.  It  is  a  good  plan  to  heel-in 
the  trees  in  the  orchard  so  that  they  will  not  have  to  be  moved  until 
planting  time,  and  then  only  as  needed. 

The  roots  of  trees  should  never  be  exposed  to  the  air  more  than  a 
minute  or  two,  especially  if  the  sun  is  shining  or  the  wind  blowing. 
The  ideal  time  to  plant  is  on  a  cloudy  day  when  the  air  is  moist.  After 
removing  the  trees  from  the  heeling-in  trench,  protect  the  roots  at  all 
times  by  covering  with  wet  burlap.  The  importance  of  protecting  the 
roots  before  planting  and  of  doing  the  planting  in  a  thorough  manner 
cannot  be  over-emphasized.  If  these  precautions  are  observed,  there 
is  no  reason  why  99  per  cent  of  the  trees  should  not  live. 


10  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

Trees  should  never  be  planted  until  the  land  has  been  thoroughly 
prepared  by  deep  plowing  and  harrowing  until  the  surface  is  fine  and 
all  lumps  broken  up.  Preferably  the  plowing  should  have  been  done 
a  wreek  or  two  previous  to  planting  so  that  the  soil  may  have  time  to 
settle.  If  there  are  intervening  rains,  the  surface  may  be  fined  again 
by  disking  or  harrowing. 

While  apricot  trees  have  been  successfully  planted  in  California  as 
late  as  early  April,  the  trees  by  that  time  are  beginning  to  leaf  out 
and  there  is  considerable  risk  of  getting  a  poor  stand  and  a  puny 
growth.  Where  possible,  the  trees  should  receive  at  least  one  good 
rain  after  planting.  A  soaking  rain  has  often  corrected  a  bad  job  of 
planting  by  settling  the  soil  about  the  roots  before  they  had  time  to 
dry  out. 

Before  newly  planted  trees  begin  to  grow,  the  tops  should  be  cut 
off  about  thirty  inches  from  the  ground.  If  there  are  any  good  branches 
where  they  are  wanted,  they  may  be  left  after  shortening  to  a  length 
or  six  or  eight  inches.  Three  such  branches  spaced  four  to  six  inches 
apart  may  be  left  and  all  others  cut  off.  As  early  as  possible  after 
planting,  the  trees  should  be  whitewashed  from  top  to  bottom  as  a 
protection  against  sunburn.  Much  of  the  injury  attributed  to  sunburn 
in  summer  undoubtedly  occurs  in  winter.  A  white  surface  reflects  the 
sunlight,  while  a  dark  surface  absorbs  the  heat  rays.  A  whitewashed 
tree  may  be  20  to  30  degrees  cooler  on  a  sunny  day  than  one  that  is 
not  whitewashed.  After  sunset  it  requires  only  a  few  minutes  for  the 
bark  to  cool  down  to  the  temperature  of  the  air.  Likewise  in  the 
morning  just  after  sunrise  there  may  be  a  quick  rise  in  the  temperature 
from  around  the  freezing  point  to  perhaps  60,  80  or  even  90  degrees, 
according  to  how  much  purple  coloring  matter  there  is  in  the  bark,  or 
whether  the  trees  are  whitewashed.  It  is  the  sudden  changes  or  great 
extremes  in  temperature  after  the  roots  have  become  active  that  cause 
bark  injury. 

Boot  Stocks  for  Apricots. — Apricots  are  chiefly  budded  upon  seed- 
ling apricot  stock,  although  peach  and  myrobalan  are  also  used.  A 
survey  of  California  nurseries  in  1919  showed  that  almost  half  the 
apricots  propagated  that  year  (49.1  per  cent)  were  on  apricot  roots, 
while  27.2  per  cent  were  on  peach  and  23.7  per  cent  on  myrobalan. 
The  apricot  often  does  not  form  a  good  union  with  the  almond,  so  at 
the  present  time  that  stock  is  not  much  used.  Seedling  apricot  is 
perhaps  the  best  all-round  stock.  Peach  root  stock  is  supposed  to 
thrive  better  than  the  apricot  in  dry  or  gravelly  soils,  while  myrobalan 
is  used  to  adapt  the  trees  to  locations  where  it  is  too  wet  for  either  the 


Circular  238]  THe  apricot  in  California  11 

apricot  or  the  peach.  While  nurserymen  ostensibly  propagate  what 
the  public  desires,  they  often  follow  their  own  personal  preferences  or 
convenience  in  the  stocks  they  use. 

Most  orchardists  prefer  to  buy  their  apricot  trees  from  a  nursery. 
However,  they  are  easily  grown  at  home.  Apricot  and  peach  seeds  are 
usually  procured  from  a  cannery  or  a  drying  establishment.  Myrobalan 
seed  or  seedlings  are  generally  obtainable  from  some  large  nursery  or 
from  an  importer.  In  the  prune  regions,  where  the  trees  are  largely 
grown  on  myrobalan  stock,  there  can  always  be  found  scattering  trees 
that  have  died  and  been  allowed  to  strout  from  the  roots.  The  fruit 
from  these  wild  myrobalans,  or  cherry  plums  as  they  are  generally 
called,  should  be  allowed  to  ripen  on  the  trees,  after  which  it  is  collected 
and  kept  in  tubs,  boxes,  or  even  in  piles  on  the  ground,  where  it  is 
allowed  to  rot,  when  the  seeds  may  easily  be  washed  from  the  pulp. 
These  are  dried  in  the  shade  and  placed  in  bags  or  boxes  of  sand  and 
buried  twelve  to  eighteen  inches  deep  until  fall. 

Any  kind  of  seed,  apricot,  peach,  or  myrobalan,  should  be  stratified 
in  shallow  boxes  of  sand  in  October  or  November.  Boxes  about  four 
inches  deep  are  best.  Place  a  layer  of  sand  an  inch  deep  in  the  bottom, 
then  a  layer  of  seed,  another  layer  of  sand,  and  so  on  until  the  box  is 
filled.  Quarter-inch  cracks  in  the  bottom  of  the  boxes  will  afford  the 
necessary  drainage.  Set  the  boxes  flat  on  the  ground  out  of  doors 
in  a  shady  place,  and  leave  them  there  until  planting  time  in  late 
January  or  early  February.  On  a  large  scale,  the  seeds  are  generally 
stratified  in  shallow  pits  in  the  ground. 

When  the  seeds  begin  to  sprout  they  are  ready  to  plant.  Plow  the 
land  deep  at  the  first  opportunity  in  winter.  At  planting  time  the 
soil  should  be  made  fine,  and  shallow  furrows  laid  off  four  feet  apart. 
The  seeds  are  planted  three  to  four  inches  apart  and  covered  two  or 
three  inches  deep.  One  pound  of  apricot  seed  should  produce  300  to 
400  trees,  peach  about  200,  and  myrobalan,  if  the  seed  is  all  viable, 
500  to  600  or  more.  Some  myrobalan  trees  produce  seed  that  gives 
95  to  96  per  cent  germination,  while  that  of  others  will  scarcely  sprout 
at  all. 

The  seedlings  should  be  cultivated  and  irrigated  like  a  garden,  and 
about  July  or  August  they  will  be  ready  to  bud.  Budding  may  be 
done  as  late  as  the  last  of  September.  Trees  may  be  budded  when 
they  have  attained  four-  or  five-sixteenths  of  an  inch  in  diameter.  Set 
the  buds  as  near  the  ground  as  possible.  The  buds  are  sliced  from 
the  twig  of  the  desired  variety  and  inserted  beneath  the  bark  of  the 
seedling,  then  tied  firmly  with  a  cotton  string  such  as  storekeepers  use. 


12  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

A  vertical  cut  an  inch  and  a  half  long  is  made  on  the  seedling,  then  a 
horizontal  cut  halfway  around  the  little  tree  at  the  top  of  the  vertical 
slit,  so  that  the  bark  can  be  raised  with  the  point  of  the  knife  and  the 
bud  pushed  downward  into  place.  In  cutting  the  buds,  it  is  immaterial 
whether  the  bark  containing  the  bud  is  peeled  off  or  sliced  off  with  a 
bit  of  wood  left  adhering.    Either  method  gives  good  results. 

The  following  spring  the  seedlings  are  cut  off  just  above  the  buds. 
If  heavy  summer  winds  are  prevalent,  the  trees  that  grow  from  the 
buds  may  have  to  be  tied  to  a  stake  to  prevent  their  breaking  off. 
The  suckers  below  the  bud  will  have  to  be  rubbed  off  about  twice,  in 
order  to  force  the  inserted  buds  to  grow.  After  growing  through  the 
season,  the  trees  are  ready  for  transplanting  to  the  orchard.  It  will 
thus  be  seen  that  one-year-old  trees  have  a  two-year-old  root  system. 
Sometimes  nursery  trees  make  a  poor  growth  the  first  year  from  the 
bud.  Such  trees  are  generally  cut  back  to  the  ground  or  to  a  single 
bud  and  allowed  to  grow  another  year,  when  they  are  still  sold  as 
one-year-olds. 

In  counting  the  age  of  trees  in  the  orchard,  it  is  customary  to 
disregard  the  time  they  spent  in  the  nursery.  In  practice,  a  five-year- 
old  orchard,  for  example,  is  a  collection  of  trees  that  have  spent  five 
growing  seasons  in  the  orchard,  although  the  root  system  may  have 
been  two  or  three  years  old  when  planted. 

PKUNING 
Pruning  properly  begins  with  the  training  of  the  young  trees  the 
first  year  in  the  orchard.  After  planting,  trees  are  generally  trimmed 
to  a  straight  whip  and  cut  off  from  twenty- four  to  thirty  inches  high. 
In  rare  cases,  nursery  branches  in  good  condition  may  occur  at  places 
where  they  are  wanted  (fig.  2) .  If  so,  they  may  be  left  after  shortening 
back  to  six  or  eight  inches  (fig.  3).  Ordinarily,  all  the  nursery 
branches  are  trimmed  off,  so  that  a  new  branch  system  must  be  grown 
from  the  dormant  buds  or  from  adventitious  buds  which  arise  from 
around  the  wounds  where  limbs  have  been  cut  off.  About  April  it  will 
be  found  that  many  buds  on  the  trunk  are  starting  to  grow,  if  the  trees 
have  not  been  injured  by  becoming  too  dry  before  being  planted.  If 
left  alone,  the  shoots  from  the  lower  buds  probably  will  become  not  more 
than  an  inch  or  two  long,  while  those  from  the  three  or  four  upper- 
most buds  will  grow  very  rapidly  and  continue  to  elongate  until  mid- 
summer or  later.  Where  the  entire  branch  system  comes  from  the  three 
or  four  topmost  buds,  the  branches  will  be  crowded,  forming  faulty 
crotches  and  a  very  undesirable  type  of  head  for  the  tree. 


Circular  238] 


THE   APRICOT   IN    CALIFORNIA 


13 


The  most  desirable  type  of  head  is  one  where  the  branches  are 
spaced  as  far  apart  as  possible  along  the  trunk.  The  ideal  plan  would 
be  to  have  three  branches,  spaced   six  inches  apart   and   arranged 


Fig.  2. — Apricot  tree  with  lateral  branches,  planted  as  received  from  the 
nursery.    For  pruning  see  Fig.  3. 

spirally  around  the  trunk.  In  other  words,  we  may  imagine  the  trunk 
as  being  the  hub  of  a  wheel,  the  three  branches  representing  the  spokes. 
This  will  describe  the  tree  with  its  three  primary  branches  as  seen 
when  looking  at  it  from  above.  The  only  way  to  cause  strong  branches 
to  grow  where  they  are  wanted  is  to  pinch  the  tips  from  the  undesirable 


14  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

young  sprouts  when  they  are  an  inch  or  two  long,  leaving  untouched 
the  three  that  are  located  where  desired.  We  usually  leave  the  topmost 
sprout,  another  about  six  inches  below  it,  and  a  third  six  inches  below 
that.  It  is  not  always  possible  to  find  three  sprouts  just  where  they 
are  wanted.  It  is  much  better  to  merely  tip  the  undesirable  sprouts 
than  to  remove  them  entirely.  Each  of  these  short  spurs  will  produce 
a  cluster  of  leaves  which  are  very  valuable,  as  they  not  only  shade  the 
trunk  and  help  to  prevent  sunburn,  but  they  help  to  manufacture  food 
for  building  up  the  roots  and  other  parts  of  the  tree.  It  is  a  good  plan 
to  examine  the  trees  again  in  June  to  see  if  any  additional  pinching 
back  of  undesirable  branches  is  necessary.  Much  can  be  done  toward 
shaping  young  trees  in  early  summer,  wThere  one  side  is  lengthening 
faster  than  another  by  pinching  off  the  tip  of  an  occasional  branch  to 
repress  the  growth. 

Pruning  One-Y  ear-Old  Trees. — The  first  winter  pruning  of  apricots 
may  be  done  in  January,  approximately  one  year  after  the  trees  were 
planted.  At  this  time,  three  scaffold  branches  are  selected  to  form  the 
framework  of  the  tree.  If  the  summer  pinching  of  the  previous  year 
has  been  a  success,  there  will  be  little  to  do,  except  perhaps  to  remove 
a  few  superfluous  branches  and  to  cut  back  the  three  scaffolds  pre- 
viously selected  to  a  length  of  from  fourteen  to  twenty-four  inches, 
according  to  the  amount  of  growth  that  has  been  made.  The  longer 
the  branches  are  left,  the  more  rapid  will  be  the  growth  of  the  trees 
the  first  year  or  two.  However,  the  apricot,  especially  in  the  coastal 
region,  is  inclined  to  make  a  very  spreading  growth,  and  if  the  scaffold 
branches  are  left  too  long  the  first  year  they  may  have  to  be  tied 
up  to  keep  them  from  drooping  over  and  sweeping  the  ground.  It  is 
usually  best,  where  the  apricot  trees  have  made  a  growth  of  two  or 
three  feet  the  first  season  to  cut  the  branches  so  that  the  parts  left  will 
have  about  the  following  lengths:  the  bottom  one  30  inches,  the  one 
next  to  it  24  inches,  and  the  top  one  18  inches.  If  the  trees  have  made 
less  growth  the  first  season,  the  length  of  the  branches  after  heading 
back  will  be  proportionately  shorter. 

In  cutting  the  tops  from  the  scaffold  branches,  it  should  be  remem- 
bered that  the  two  uppermost  buds  left  are  expected  to  form  the 
branches  that  are  to  complete  the  framework  of  the  tree.  It  is 
important  to  see  that  these  two  buds  point  in  the  directions  it  is  desired 
to  have  the  branches  grow.  The  only  object  in  heading  back  a  young 
tree  is  to  secure  additional  branches  where  they  may  be  needed. 
Theoretically,  the  three  branches  that  have  been  headed  back  should 
yield   six  branches.     However,  buds  do  not  always  grow  exactly  as 


Circular  238] 


THE    APRICOT   IN    CALIFORNIA 


15 


planned.  It  is  usually  possible  to  secure  five  satisfactory  branches 
from  the  six  chances,  and  fortunately  five  are  enough  to  form  a  very 
desirable  system  of  main  branches  on  any  tree,  whether  it  be  apricot 
or  some  other  deciduous  species. 

With  proper  soil  and  moisture  conditions,  apricot  trees  usually 
make  a  vigorous  growth  during  their  second  season  in  the  orchard. 
The  three  scaffold  branches  left  from  the  first  dormant  pruning  will 
grow  not  only  from  the  two  or  three  topmost  buds  of  each,  but  many 


Fig. 


3. — Lateral  branches,  if  well  spaced,  are  left,  but  are  shortened  to 
six  or  eight  inches  when  the  tree  is  planted.     See  Fig.  2. 


of  the  side  buds  will  grow  into  spurs,  and  occasionally  one  will  form  a 
branch.  In  addition,  vigorous  shoots  may  arise  from  around  the  points 
where  small  branches  have  been  cut  out.  Any  little  spurs  that  may 
have  been  left  on  the  trunk  will  very  probably  elongate  a  few  inches. 
Sometimes  only  a  comparatively  few  of  the  side  buds  on  the  scaffold 
branches  grow  at  all  the  first  year.  Those  that  remain  dormant  during 
the  first  season  may  begin  to  push  the  second  or  even  the  third  year, 
but  little  can  be  expected  of  those  that  fail  to  start  the  first  or  second 
season. 

The  first  fruit  the  trees  produce  may  be  expected  to  come  largely 
from  the  spurs  that  grow  from  the  side  buds  on  the  scaffold  branches. 
Some  will  come  from  the  spurs  which  were  left  on  the  trunk  the  pre- 
vious year  or  which  may  arise  from  dormant  or  adventitious  buds 


16  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

during  the  second  season's  growth  in  the  orchard.  It  is  during  the 
second  season  that  the  buds  are  formed  which  produce  the  first  crop 
of  fruit  during  the  third  season  of  growth. 

During  the  second  season  in  the  orchard,  if  growth  is  vigorous, 
many  sprouts  from  around  the  pruning  wounds,  or  even  from  dormant 
buds',  may  be  produced  where  they  are  not  wanted.  It  is  a  good  plan 
to  go  through  the  orchard  about  the  first  of  May  or  whenever  the 
sprouts  are  eight  or  ten  inches  long  and  pull  off  those  that  are  not 
wanted,  and  perhaps  pinch  the  tips  from  others  that  are  placed  where 
they  will  make  desirable  fruit  spurs.  The  pinching  is  to  check  the 
length  growth  and  cause  the  side  buds  to  be  pushed  out.  At  the  same 
time,  some  assistance  may  be  rendered  to  the  main  outgrowths  from 
near  the  tips  of  the  scaffold  branches  by  pinching  back  those  that  are 
clearly  out  of  line,  or  where  growth  is  uneven  or  unsymmetrical. 
Sometimes  one  or  two  branches  are  inclined  to  outgrow  all  the  others, 
which  tendency,  if  not  corrected  very  early,  may  result  in  a  very 
unshapely  tree  and  greatly  increase  the  pruning  difficulties  the  follow- 
ing winter. 

Pruning  during  the  Second  Season. — "When  the  leaves  have  fallen 
after  the  second  season 's  growth  in  the  orchard,  the  trees  are  ready  for 
their  second  dormant  pruning.  It  is  not  advisable  to  prune  an  apricot 
of  any  age  before  the  leaves  have  fallen.  The  leaves  of  any  deciduous 
tree  perform  a  valuable  function,  and  they  are  useful  to  the  tree,  even 
in  late  summer  and  early  fall,  so  long  as  they  remain  green  and  are 
firmly  attached  to  the  twigs. 

The  pruning  of  two-year-old  apricot  trees  that  have  made  a  satis- 
factory growth  is  a  comparatively  simple  matter  if  the  pinching  the 
previous  summer  was  properly  done.  It  should  be  remembered  at  this 
time  that  five  good  main  branches,  properly  distributed,  are  sufficient 
to  form  the  framework  of  the  tree.  Sometimes  the  trees  have  a 
sufficient  branch  spread  and  the  branches  are  so  arranged  that  it  is 
advisable  to  leave  six  instead  of  five.  This  is  perhaps  more  apt  to  be 
true  of  apricots  than  of  most  other  species  of  deciduous  fruits,  because 
of  the  spreading  habit  of  the  trees.  Along  the  coast  and  in  the  coastal 
valleys  there  is  some  danger  that  two-year-old  apricot  trees  may  assume 
an  extremely  spreading  habit,  and  thus  cause  the  main  branches  to  be 
so  low  as  to  interfere  with  cultivation.  Fortunately,  the  apricot  takes 
kindly  to  having  this  condition  rectified  by  passing  a  cord  around  the 
tree  outside  the  branches  and  drawing  it  just  tight  enough  to  hold  them 
all  in  place.  This  is  easily  done  if  all  the  branches  are  of  approxi- 
mately the  same  size  and  if  the  growth  has  been  symmetrical.  Other- 
wise, it  may  be  necessary  to  tie  the  branches  that  are  out  of  place  to  a 


Circular  238] 


THE    APRICOT    IN    CALIFORNIA 


17 


stake  driven  by  the  side  of  the  tree  for  the  purpose.  The  apricot  is 
different  from  all  other  deciduous  trees  in  that  the  branches  do  not 
lean  away  from  the  prevailing  wind,  but,  on  the  contrary,  are  inclined 
to  grow  toward  the  wind. 


m 


\  i? 


4/.  km./  m 


Fig.  4. — Two-year-old  apricot  trees  often  grow  very  rapidly,  and  severe 
thinning  is  necessary.     See  Fig.  5. 


In  pruning  two-year-old  trees,  it  will  rarely  be  necessary  to  cut  off 
any  of  the  tips  of  the  main  branches  (fig.  4).  Considerable  thinning 
may  have  to  be  done  by  removing  unnecessary  branches  (fig.  5) .  Each 
branch  on  a  well-grown  two-year-old  tree  may  be  expected  to  show  one 


18  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

and  often  two  clusters  of  small  twigs  from  four  to  twelve  inches  long. 
These  clusters  of  twigs  are  called  fruiting  whorls.  Where  the  new 
growth  is  only  two  or  three  feet  long,  it  is  rarely  necessary  to  cut  off 
the  tips.  However,  it  is  usually  desirable  to  thin  the  fruiting  whorls 
by  removing  about  half  the  twigs  with  the  pruning  shears.  If  the  total 
new  growth  is  four  or  five  feet  long  or  longer,  and  there  is  a  long  whip 
even  beyond  the  first  or  second  fruiting  whorl  which  has  curved,  under 
its  own  weight,  and  points  toward  the  ground,  the  branch  may  be 
headed  back  to  the  last  fruiting  whorl.  However,  it  is  well  to  first  tie 
up  such  branches  before  cutting  off  the  tips  to  see  if  the  cutting  may 
not  be  avoided. 

Fortunately,  a  tree  seems  to  secure  practically  all  of  the  benefits 
of  long  pruning,  even  where  branches  are  headed  back,  if  the  cuts  are 
made  outside  the  fruiting  whorl.  Still  it  should  be  remembered  that 
every  bud  left  toward  the  tip  of  a  branch  is  valuable  for  making  early 
maturing  leaves  the  next  season.  Also,  the  more  leaves  there  are  on  a 
tree,  provided  all  are  exposed  to  the  light,  the  more  rapid  will  be  the 
growth  of  the  tree,  especially  as  measured  by  diameter  of  trunk  and 
main  branches.  Hence  the  necessity  for  carefully  thinning  out  twigs 
and  even  branches  where  the  leaves  are  likely  to  be  crowded. 

The  pruning  during  the  first  and  second  seasons  is  for  the  purpose 
of  giving  proper  shape  to  the  trees,  but  the  third  year  we  begin  to  have 
some  regard  for  fruit  production.  Some  pinching  and  suckering  may 
be  desirable  during  the  third  summer.  At  this  time  well-grown  trees 
should  set  a  considerable  amount  of  fruit,  Indeed  it  would  not  be 
detrimental  in  any  way  if  the  trees  should  ripen  from  ten  to  twenty 
pounds  of  fruit  each  during  their  third  season  in  the  orchard.  Most 
of  the  fruit  will  be  produced  on  the  spurs  two  or  three  feet  from  the 
ground.  Buds  on  the  fruiting  whorls  of  the  main  branches  and  even 
the  side  buds  farther  out  may  bloom  and  even  set  fruit,  but  only  along 
the  coast  is  this  fruit  likely  to  stay  on  and  ripen.  Where  the  fruit  does 
stay  on  far  out  on  the  main  branches  at  this  time,  it  may  be  necessary 
to  thin  it  severely,  or  even  to  remove  it  entirely  if  the  branches  seem 
to  be  unduly  weighted  down  or  thrown  out  of  place  by  heavy  winds. 
At  this  time,  the  shape  of  the  tree  is  a  far  more  important  matter  than 
the  production  of  a  few  extra  pounds  of  fruit.  In  the  interior  valley 
sections',  there  is  not  likely  to  be  much  difficulty  from  the  production 
of  fruit  toward  the  tips  of  the  new  branches  on  trees  of  any  age,  but 
along  the  coast  this  is  a  real  problem,  even  with  old  trees,  especially 
where  the  pruning  system  has  been  changed  from  the  short  to  the 
long  method  and  consequently  the  new  branches  may  be  very  long. 


Circular  238] 


THE   APRICOT    IN    CALIFORNIA 


19 


In  addition  to  the  five  main  branches  that  are  left  at  the  second 
winter  priming,  there  are  apt  to  be  several  switches  from  one  to  two 
feet  long  aronnd  the  outside  of  the  trees.      These  are  regarded  as 


Fig.  5. — Thinning  out  superfluous  branches  admits  sunlight  to  the  center 
of  the  tree  and  promotes  growth  of  fruit  spurs.    See  Fig.  4. 

temporary  fruiting  branches,  and  are  not  cut  off  where  they  are  not 
crowding  each  other.  It  is,  however,  advisable  to  shorten  them  by 
removing  six  to  ten  inches  from  the  tips  to  prevent  them  from  making 
too  much  diameter  growth.    Since  their  position  on  the  outside  of  the 


20  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

trees  is  such  that  they  will  not  shade  any  of  the  spurs,  they  are  left  for 
the  benefit  of  the  leaves  they  will  bear,  and  also  to  produce  from  one  to 
three  crops  of  fruit,  after  which  they  may  be  removed  if  they  are 
getting  in  the  way  of  cultivation.  By  keeping  them  small  by  cutting 
off  the  tips  each  year,  they  can  be  easily  removed  at  any  time  they  are 
no  longer  desired. 

After  apricot  trees  have  come  into  fruiting,  the  plan  of  pruning  is 
much  the  same  year  by  year.  No  heading  back  should  be  practiced  as 
long  as  the  trees  are  making  a  reasonable  growth  and  the  fruit  sizes 
up  well.  Scarcity  of  moisture  in  the  soil  during  the  growing  season 
or  in  the  fall  when  buds  should  be  forming  for  the  next  year's  crop 
may  greatly  reduce  the  annual  growth,  and  may  prevent  the  fruit  from 
attaining  a  marketable  size.  Canneries  now  buy  fruit  according  to 
size,  and  their  tendency  is  to  demand  larger  sizes.  Dried  fruit  also  is 
graded  according  to  size,  and  the  price  differential  between  the  larger 
and  smaller  sizes  is  sufficiently  great  to  make  a  big  difference  in  the 
value  of  the  crop. 

The  aim  of  the  primer  should  be  to  keep  the  head  of  the  tree  open 
so  that  every  leaf  gets  its  share  of  the  sunlight.  Every  main  branch 
and  subordinate  branch  should  be  clothed  with  fruiting  spurs  five  to 
ten  inches  apart.  If  there  are  too  many  main  branches,  the  spurs, 
especially  on  the  older  wood,  gradually  die  out.  It  is  perfectly  normal 
for  an  apricot  spur  to  die  after  three  or  four  years,  but  if  sufficient 
light  is  admitted  to  all  parts  of  the  tree,  new  sprouts  which  make  spurs 
quickly  arise  from  around  the  base  of  the  spurs  that  have  died.  Often 
water  sprouts  arise  from  the  old  wood  in  various  parts  of  the  tree 
which  can  be  converted  into  fruiting  spurs.  Pinching  these  in  early 
summer  has  a  tendency  to  prevent  them  from  becoming  too  long,  a 
condition  hard  to  remedy  at  pruning  time  in  winter.  If  water  sprouts 
have  not  been  shortened  in  summer,  the  procedure  at  regular  pruning 
time  is  to  leave  them  uncut  unless  they  are  so  long  as  to  interfere  with 
other  branches  if  being  devoted  to  production  of  side  limbs  or  spurs 
from  most  of  the  dormant  buds.  The  following  year  they  may  be  cut 
back  to  one  of  the  side  limbs  or  spurs,  with  the  assurance  that  they 
will  seldom  or  never  sprout. 

Pruning  during  the  Third  Season  and  Afterward. — In  the  main, 
the  pruning  of  bearing  apricots  consists  in  an  annual  thinning  through- 
out the  entire  tree  so  that  every  twig  and  leaf  is  exposed  to  sunlight 
during  at  least  some  part  of  the  day  (fig.  6).  If  no  heading  back  is 
practiced,  the  long  branches  sway  in  the  wind  and  the  sunlight  filters 
through  the  trees,  but  does  not  shine  on  any  bare  spot  on  the  branches 


Circular  238] 


THE    APRICOT   IN    CALIFORNIA 


21 


for  more  than  a  few  minutes  at  a  time.  Such  trees  will  never  suffer 
from  sunburn.  It  will  be  necessary  to  remove  annually  many  small 
branches,  but  very  few  larger  than  an  inch  in  diameter.  If  there  are 
too  many  branches,  either  cut  out  entirely  those  which  are  superfluous, 
or  reduce  their  length  by  cutting  to  a  side  branch,  but  do  not  head 
them  back. 


Fig.  6. — An  abundance  of  fruit  spurs  on  the  main  branches  are  produced  by 
"long  pruning."     This  four-year-old  tree  is  ready  for  a  heavy  crop. 


The  temporary  fruiting  branches  will  again  need  attention  in  the 
way  of  cutting  off  the  tips  if  they  are  inclined  to  continue  to  elongate. 
The  second  year  they  should  bear  several  spurs,  and  they  may  be  cut 
off  to  one  of  these.  New  switches  suitable  for  more  temporary  branches 
may  have  to  be  tipped.  Sometimes  new  branches  may  arise  high  up  on 
the  outside  of  the  main  branches  and  compete  with  these  for  leader- 
ship. The  remedy  is  to  cut  them  back  so  that  they  are  six  to  twelve 
inches  shorter  than  the  leaders,  thus  converting  them  into  fruiting 
branches  that  may  be  permanent  or  temporary. 


22  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Never  allow  a  sucker  or  normal  side  branch  to  grow  up  undisturbed 
on  the  outside  of  a  leader.  Owing  to  their  more  favorable  position, 
such  branches  are  almost  sure  to  outgrow  the  leader  and  to  overcome 
it  in  about  three  years.  As  before  stated,  the  remedy  is  to  cut  off  the 
tops  of  such  branches  when  they  are  one  or,  at  the  latest,  two  years  old. 

Long  pruning  of  bearing  trees  tends  to  make  them  fruit  heavily. 
Just  how  many  pounds  of  fruit  a  given  tree  can  produce  can  be 
determined  only  by  the  person  who  has  the  constant  care  of  that  tree 
throughout  the  season,  and  who  sees  it  when  the  fruit  is  harvested 
and  observes  the  quality  of  the  product,  especially  its  size  and  color, 
and  then  observes  what  effect  the  yield  has  upon  the  vigor  of  the  tree. 
The  effect  of  over-fruiting  is  usually  shown  by  the  small  size  of  the 
fruit  and  a  diminution  in  growth  of  the  tree.  Trees  five  and  six  years 
old,  even  under  heavy  fruiting,  should  make  a  twig  growth  on  the  ends 
of  the  main  branches  from  twelve  to  twenty  inches  long ;  mature  trees, 
twelve  to  fifteen  or  twenty  years  of  age,  should  every  year  make  eight 
to  ten  inches  of  twig  growth,  and  even  very  old  trees  should  make 
four  or  five  inches  annually.  However,  these  figures  are  only  approxi- 
mate. The  experienced  grower  should  be  able  to  judge  from  the 
appearance  of  the  trees,  and  especially  from  the  appearance  of  the 
fruit,  whether  they  are  being  cropped  too  heavily. 

The  amount  of  moisture  in  the  first  five  or  six  feet  of  soil  during 
the  growing  season  will  be  the  chief  limiting  factor  in  determining  the 
quantity  of  high-grade  fruit  the  trees  can  produce.  If  irrigation  is 
practiced  to  supplement  this  initial  amount  of  moisture,  the  trees  may 
be  expected  to  mature  more  fruit  than  where  the  orchard  is  entirely 
dependent  upon  rainfall.  The  grower  will  have  to  judge  the  produc- 
tive limit  of  the  trees  by  their  behavior  and  prune  accordingly,  for  he 
has  it  within  his  power  to  leave  them  with  either  a  large  or  a  small 
bearing  surface.  It  should  be  remembered,  however,  that  long  pruning 
applies  both  to  trees  without  irrigation  and  with  it.  Long  pruning 
should  under  any  circumstances  increase  the  yield  from  15  to  20  per 
cent  over  what  would  ordinarily  be  secured  under  the  old  method  of 
annual  heading  back,  but  the  greatest  increase  is  possible  only  where 
there  are  facilities  for  summer  and  early  fall  irrigation. 

If  the  heavy  heading  back  of  young  trees  is  a  devitalizing  process, 
and  this  point  has  been  amply  demonstrated,  it  is  only  reasonable  to 
conclude  that  old  trees  would  be  similarly  affected.  Under  the  long- 
pruning  method,  the  valuable  buds  at  the  ends  of  the  twigs  are  pre- 
served and  the  trees  are  thereby  invigorated  and  enabled  to  produce 
more  fruit,  and  yet  come  through  the  season  in  as  good  condition  or 


Circular  238]  THE  APRICOT  IN   CALIFORNIA  23 

better  than  if  they  had  produced  less  under  the  old  system  of  heavy 
annual  heading  back  of  most  of  the  new  growth. 

The  question  is  often  raised  as  to  whether  it  will  ever  be  necessary 
to  cut  back  trees  under  the  long-pruning  system.  The  time  may  come, 
especially  where  the  pruning  system  has  been  changed  from  the  short 
to  the  long  on  bearing  trees,  when  it  may  be  advisable  to  reduce  the 
tops  by  cutting  back  to  lateral  branches  for  the  purpose  of  renewing 
the  wood  growth.  Trees  may  have  been  allowed  to  overbear  through 
leaving  too  many  branches,  or  the  soil  moisture  may  have  been  in- 
adequate and  the  growth  reduced  to  a  dangerous  degree.  Under  such 
circumstances,  removal  of  a  portion  of  the  tops,  coupled  with  a  severe 
thinning  of  the  smaller  branches,  wrill  result  in  a  rejuvenation  of  the 
trees  throughout  by  causing  many  new  sprouts  to  grow  on  all  the 
remaining  branches. 

Changing  the  Pruning  System. — The  question  is  frequently  asked 
how  to  change  the  system  of  pruning  on  trees  from  ten  to  twenty 
years  of  age  or  older,  from  the  old  or  heavy  heading-back  method  to 
the  so-called  long-pruning  system  advocated  by  the  University  of 
California,  provided  such  a  change  is  advisable.  Answering  the  last 
part  of  the  question  first,  it  may  be  said  that  apricot  trees  of  any  age 
are  better  off  not  to  have  the  new  growth  headed  back  year  after  year. 
It  is  true,  however,  that  the  benefits  of  long  pruning  on  very  old  trees 
that  are  making  but  little  growth  may  not  be  noticeable  the  first  year 
or  two  after  the  change  is  made.  But  if  they  are  capable  of  being 
revived,  long  pruning  will  be  the  best  treatment  to  give  them. 

Unless  the  trees  have  been  grown  with  more  than  ordinarily  open 
heads,  the  first  step  to  be  taken  in  changing  the  pruning  system  from 
the  old  to  the  new  is  to  give  them  a  severe  thinning  (fig.  7).  It  may 
be  necessary  to  remove  from  two  or  three  to  a  half-dozen  old  branches 
two  or  three  inches  in  diameter.  But  the  heads  must  be  opened  out 
at  all  hazards  since,  if  too  many  branches  were  left,  the  main  objects 
to  be  attained  by  long  pruning  would  be  defeated.  Here  is  where  the 
first  mistake  has  been  to  leave  too  many  of  the  one-year-old  sprouts 
on  the  stumps  where  the  heavy  heading  was  done  the  previous  year. 

But  how  many  branches  and  sprouts  should  be  left  ?  Of  course,  the 
main  framework  of  the  trees  has  already  been  fixed  and  must  be 
accepted.  At  a  height  of  four  and  a  half  feet  from  the  ground  there 
should  be  five  or  six  upright  branches.  Two  feet  higher  up,  there 
should  be  perhaps  eight  or  ten  branches,  but  no  more,  unless  the  trees 
are  exceptionally  large.  An  apricot  tree  with  a  top  diameter  of  twelve 
feet  may  possibly  have  eighteen  to  twenty  branches  at  a  point  nine 


24  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

or  ten  feet  from  the  ground.  In  the  extreme  top,  where  the  mass  of 
one-year-old  shoots  are  located,  rigid  thinning  should  be  practiced 
until  the  young  branches  remaining  stand  eighteen  inches  to  two  feet 
apart  at  their  tops.  Often  three  to  five  shoots  grow  from  a  single  stub. 
Many  of  these  stubs  should  be  removed,  and  the  growth  on  the  rest 
thinned  to  one  shoot. 

If  the  new  shoots  in  the  tops  are  three  to  four  feet  long,  it  is  often 
a  question  whether  they  should  be  topped  lightly,  that  is,  above  the 
main  fruiting  whorl.  In  general,  no  topping  is  necessary  in  the 
interior  valley  sections,  as  the  fruit  buds  on  these  parts  may  bloom  and 
even  set  fruit,  but  most  of  it  will  be  likely  to  fall  off.  Along  the  coast, 
however,  all  the  fruit  may  remain  and  the  weight,  coupled  with  the 
strong  prevailing  winds,  may  cause  some  breakage  to  the  branches. 
Also  the  fruit  on  these  one-year-old  sprouts  is  the  least  valuable  of 
any  on  the  trees,  as  it  often  does  not  size  well  and  is  liable  to  be  sun- 
burned. Instead  of  topping  these  branches,  some  growers  prefer  to 
knock  the  fruit  off  with  a  pole  tipped  with  a  piece  of  rubber  hose  to 
prevent  injury  to  the  bark. 

One  of  the  first  effects  of  opening  out  the  head  of  an  old  tree  is  a 
more  or  less  abundant  growth  of  new  spurs  up  and  down  the  bare 
branches.  New  sprouts  will  continue  to  break  out  from  the  old  wood 
for  the  first  three  years.  The  second  year  after  a  sprout  arises  it  begins 
to  bear  fruit.  It  is  desirable  to  have  these  spurs  extend  down  to 
within  a  foot  or  two  of  the  ground  if  possible,  as  they  will  produce 
some  of  the  best  fruit  on  the  trees. 

It  is  a  mistake  to  think  that  trees  will  continue  to  grow  higher  and 
higher  if  the  tops  are  not  cut  off.  If  the  sprouts  at  the  top  are  three 
feet  long  when  the  pruning  system  is  changed,  they  will  grow  about 
eighteen  inches  the  first  year,  ten  or  twelve  the  second,  five  or  six  the 
third  year,  and  no  more  than  six  inches  any  year  thereafter.  The  first 
season,  the  trees  will  actually  be  about  two  feet  taller  than  under  the 
old  system  of  cutting  back  to  ten  or  twelve  inch  stubs,  but  after  that 
period  they  will  droop  over  under  their  load  of  fruit,  and  the  entire 
branches  will  tend  to  lean  outward  so  that  the  net  result  is  lower  than 
before.  Of  course,  trees  that  have  been  short  pruned  for  a  considerable 
time  will  have  been  carried  high  in  the  air,  a  foot  or  so  a  year,  and 
such  trees  cannot  be  lowered  very  much,  but  their  further  upward 
growth  is  effectually  stopped  by  not  cutting  off  the  tops. 

Very  rarely  does  a  grower  remove  enough  branches  from  bearing 
trees  the  first  year,  but  as  time  goes  on  he  learns  that  more  thinning 
is  necessary  and  does  not  hesitate  to  remove  more  and  more  branches, 


Circular  238] 


THE    APRICOT    IN    CALIFORNIA 


25 


both  large  and  small.  As  the  remaining  branches  fill  up  with  spurs, 
the  load  is  transferred  from  the  extreme  top  of  the  trees  to  sturdier 
parts  below,  which  are  able  to  support  it.  Thus  it  is  that  long-pruned 
trees  bear  heavier  loads  than  before,  fewer  props  are  needed,  and  there 
is  less  breakage. 

Wire  Braces  vs.  Props. — Apricot  trees  that  have  been  long  pruned 
from  the  beginning  may  never  need  propping  or  bracing,  but  old  trees, 


Fig.  7. — Old  trees  are  given  a  severe  thinning  out  when  changing  from  the 
" short"  to  the  "long"  system  of  pruning.  Fruit  wood  was  produced  on  the 
main  branches  in  the  center  of  this  thirty-year-old  tree  in  two  years  by  following 
the  long  system. 

even  when  the  pruning  system  has  been  changed  from  the  short  to 
the  long  method,  may  need  some  support.  Where  the  branch  system 
is  not  too  spreading,  that  is,  the  branches  are  not  too  horizontal,  a 
system  of  wire  braces  is  superior  to  props.  Perhaps  the  best  plan  yet 
devised  for  supporting  branches  to  prevent  their  breaking  under  heavy 
loads  of  fruit  is  to  attach  one  end  of  a  wire  to  a  branch  and  the  other 
to  a  small  iron  ring.  The  position  of  the  ring  will  be  approximately 
in  the  center  of  the  head  from  top  to  bottom.  The  wires  are  attached 
to  the  inside  of  the  branches  by  means  of  small  iron  fence  staples 
driven  completely  into  the  wood.  Both  wire  and  staples  should  be 
galvanized  so  they  will  not  rust.     The  wire  should  be  about  No.  14. 


26  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

Staples  are  cheaper  and  fully  as  satisfactory  as  screw  eyes.  A  system 
of  wire  braces  in  a  mature  orchard  should  not  cost  over  $40  an  acre 
for  labor  and  materials.  The  wires  last  indefinitely,  and  the  main- 
tenance expense  is  very  slight,  as  they  rarely  break. 

CULTIVATION 

Apricots  require  no  special  attention  in  the  way  of  cultivation.  If 
there  is  a  cover  crop  in  the  orchard,  the  first  plowing  may.  be  done  at 
such  time  as  the  greatest  tonnage  of  vegetable  matter  can  be  turned 
under.  It  is  not  advisable  to  plow  the  land  at  the  same  depth  every 
year.  In  general  deep  plowing  should  be  preferred,  that  is,  from  six 
to  ten  inches.  Plowing  at  the  same  depth  every  year,  especially  with 
a  moldboard  plow,  is  liable  to  bring  about  the  condition  known  as 
"plow-pan,"  especially  in  soils  containing  a  high  percentage  of  clay. 

Effective  work  may  be  done  with  either  moldboard  plows  or  disc 
plows.  If  the  cover  crop  is  heavy,  it  may  be  dragged  under  by  means 
of  a  heavy  chain  attached  to  the  double-trees  or  drawbar  at  one  end 
and  to  the  plow  beam  at  the  other,  and  trailing  in  such  a  manner  as 
will  best  hold  the  vegetation  down  until  caught  by  the  soil  as  it  rolls 
over. 

Where  no  irrigation  is  practiced,  it  is  important  to  do  the  spring 
plowing  early  enough  to  catch  one  or  more  good  rains.  Plowing  should 
certainly  not  be  delayed  until  the  vegetation  has  exhausted  the  moisture 
from  the  upper  soil.  "Where  irrigation  water  is  available,  plowing  may 
be  delayed  until  some  time  in  April  or  until  after  the  cover  crop  has 
begun  to  mature.  In  this  way  the  greatest  tonnage  of  dry  material 
can  be  added  to  the  soil,  and  the  irrigation  water  will  cause  it  to  rot. 

Where  orchard  heating  is  practiced,  it  may  be  desirable  to  plow 
before  the  trees  bloom,  as  it  is  more  convenient  to  handle  the  orchard 
heaters  on  bare  land  than  where  there  is  much  vegetation.  There  is 
no  evidence  to  show  that  plowing  just  before  or  during  blooming  time 
will  have  any  effect  on  the  bloom  or  the  setting  of  the  fruit,  and  neither 
is  there  any  available  proof  that  an  irrigation  at  this  time  will  in  any 
way  affect  the  bloom  or  fruit-set.  Before  the  surface  of  the  plowed 
soil  becomes  baked,  it  may  be  double-disked  and  then  smoothed  with 
a  harrow.  In  case  it  seems  unduly  porous  or  has  many  lumps  or  clods, 
it  may  be  firmed  and  smoothed  effectively  with  a  corrugated  roller. 
In  the  absence  of  a  roller,  a  heavy  drag  will  accomplish  practically 
the  same  results. 

If  morning-glory  or  bindweed  is  abundant,  it  is  well  to  use  a  weed 
cutter.     By  using  the  weed  cutter  once  a  week  throughout  the  season, 


Circular  238]  the  APRICOT  IN  CALIFORNIA  27 

all  the  morning-glories  may  be  practically  eradicated  in  one  season. 
The  best  type  of  weed  cutter  has  sloping  blades  that  run  three  to  four 
inches  below  the  surface  of  the  soil,  so  that  all  weeds  are  cut  off  at 
this  depth.  To  kill  the  morning-glory,  the  plants  must  never  be 
allowed  to  show  above  the  ground  during  the  season.  Green  leaves, 
if  allowed  to  form,  quickly  manufacture  a  new  supply  of  starch  for 
feeding  the  roots.  It  is  thus  seen  that  killing  this  weed  depends  upon 
allowing  no  leaves  to  come  to  the  surface  and  thereby  eventually 
starving  the  roots.  It  should  be  remembered  that  weeds  of  any  kind 
in  the  orchard  are  detrimental,  as  they  consume  considerable  quantities 
of  moisture  from  the  soil. 

The  chief  objects  to  be  attained  by  cultivation  are  the  following : 

(1)  by  plowing  to  turn  under  the  cover  crop,  to  stir  the  soil  that  has 
been  compacted  by  the  winter  rains,  and  to  fit  it  for  irrigation  by 
loosening  the  surface  layers  so  that  levees  can  be  thrown  up ;   and 

(2)  by  disking  and  harrowing  to  fine  the  surface  to  prevent  the  loss 
of  moisture  by  baking  and  cracking  under  the  heat  of  the  sun,  and  also 
to  keep  down  weeds. 

Recent  experiments  indicate  that  losses  of  soil  moisture  by  direct 
evaporation  from  the  soil  surface  are  negligible  as  compared  with  the 
amounts  taken  out  by  the  trees  and  other  vegetation.  The  feeding 
roots  of  apricot  trees  probably  penetrate  to  depths  of  from  three  to 
six  feet,  according  to  the  character  of  the  subsoil  and  the  amount  of 
available  moisture.  Where  apricots  are  most  largely  grown,  the  winter 
rains  are  usually  sufficient  to  wet  to  a  depth  of  from  four  to  six  feet. 
If  the  winter  rainfall  is  known  to  be  insufficient  to  wet  the  ground  five 
or  six  feet  deep,  it  is  advisable  to  irrigate  in  late  fall.  With  this  excep- 
tion, it  is  not  believed  that  irrigation  water  would  serve  any  useful 
purpose  when  applied  other  than  during  the  growing  season  or  while 
the  trees  are  still  covered  with  green  leaves. 

When  the  land  has  been  plowed  and  brought  to  a  good  state  of  tilth, 
little  cultivation  will  be  needed  during  the  remainder  of  the  summer, 
except  to  kill  weeds  and  to  put  the  soil  in  good  condition  after  an 
irrigation.  Continued  cultivation  after  the  surface  has  been  put  in 
good  condition  is  probably  an  unnecessary  expense.* 

COVER  CROPS 
Melilotus  indica,  variously  called  bee  clover,  sweet  clover,  or  bitter 
clover,  is  probably  the  most  valuable  cover  crop  for  most  orchards. 
To  secure  a  good  stand  and  a  satisfactory  growth  throughout  the 

*  An.  Rept.  Cal.  Agric.  Expt.  Sta.,  1920,  p.  45. 


28  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

winter  and  spring,  it  is  necessary  to  do  the  seeding  very  early,  prefer- 
ably in  August  or  early  September.  However,  this  early  seeding  is 
possible  only  where  irrigation  water  is  available.  If  there  is  no  fall 
irrigation,  seeding  cannot  be  done  before  the  autumn  rains  begin. 
Where  there  is  no  irrigation  water,  the  safest  cover  crop  is  barley  or 
rye.  Sometimes  a  satisfactory  growth  of  vetch  (Vicia  sativa)  may  be 
secured  by  seeding  in  early  November,  although  there  is  no  assurance 
of  a  good  stand  and  a  heavy  tonnage  unless  the  seeding  is  done  at 
least  a  month  earlier.  The  Canada  pea  will  germinate  even  in  late 
fall  and  will  continue  to  grow  throughout  the  winter,  but  the  tonnage 
of  green  matter  is  too  light  to  make  it  a  success  as  an  orchard  cover 
crop.  In  some  sections  bur  clover  is  the  best  cover  crop  that  can  be 
used,  as  it  often  reseeds  the  ground  and  continues  to  come  up  year 
by  year,  especially  in  regions  of  early  autumn  rainfall  or  where  the 
orchard  is  irrigated  in  September. 

The  following  quantities  of  seed  per  acre  should  give  good  results : 
Melilotus,  20-25  lbs. ;  bur  clover,  20  lbs. ;  vetch,  50  lbs. ;  barley  or  rye, 
50  lbs. 

IRRIGATION 

The  apricot,  like  most  other  deciduous  fruits,  requires  irrigation 
after  the  trees  come  into  bearing,  and  sometimes  before.  In  most  of  the 
apricot  districts  of  Northern  and  Central  California,  the  winter  rain- 
fall is  sufficient  to  carry  young  trees  through  the  summer  without 
irrigation.  However,  vigorous  growth  is  a  question  of  soil  supply, 
and  if  it  is  found  in  any  district  that  trees  are  not  growing  properly, 
owing  to  insufficient  moisture,  the  remedy  is  to  irrigate.  There  are 
a  few  limited  sections  where,  owing  to  peculiar  conditions  of  soil, 
rainfall  and  sea  fogs,  successful  crops  are  produced  without  irrigation, 
but  it  is  highly  probable  that  they  too  would  be  benefited  by  the 
application  of  water. 

In  the  principal  districts  of  the  state,  including  both  the  interior 
and  coastal  valleys  and  the  foothills,  apricot  growing  is  not  usually 
profitable  where  no  irrigation  is  practiced.  While  the  trees  themselves 
may  not  die,  they  do  not  make  a  thrifty  growth,  and  are  very  apt  to 
decline  rapidly  in  vigor  after  a  few  crops  have  been  produced.  The 
yields  under  such  conditions  are  apt  to  be  irregular. 

Irrigation  should  begin  in  March  or  not  later  than  the  first  of  April 
if  the  winter  rainfall  has  not  wet  the  ground  to  a  depth  of  six  feet. 
If  the  ground  has  been  wet  to  that  depth  no  further  irrigation  will  be 
necessary  until  May  or  June.  If  the  soil  has  been  kept  moist  and  the 
trees  in  a  continuous  growing  condition,  there  need  be  no  harmful 
results   in    irrigating  near   ripening  time,   but   canneries   sometimes 


Circular  238]  THE  APRICOT  IN  CALIFORNIA  29 

object  to  taking  fruit  irrigated  so  late,  in  the  belief  that  the  quality 
will  be  lowered,  although  there  is  no  evidence  to  substantiate  this 
belief.  In  regions  where  apricots  are  grown  chiefly  for  canning  pur- 
poses, it  is  found  necessary  to  irrigate  sometimes  about  the  first  or  the 
middle  of  May  in  the  interior  valley  sections,  and  between  the  middle  of 
May  and  the  middle  of  June  along  the  coast,  where  the  season  of  ripen- 
ing is  later.  An  early  summer  irrigation  seems  to  be  necessary  to  obtain 
fruit  of  the  size  demanded  by  the  canneries,  and  does  not  seem  in  any 
way  to  lower  the  quality.  As  a  rule,  the  canneries  will  not  take  fruit 
requiring  more  than  twelve  or  fourteen  to  make  a  pound.  If  the  trees 
are  suffering  for  moisture,  an  early  summer  irrigation  within  two  or 
three  weeks  of  ripening  is  apt  to  crack  the  fruit,  but  there  is  no  danger 
of  this  if  they  have  been  kept  in  good  growing  condition.  Growers  of 
apricots  for  drying  purposes  have  not  given  so  much  attention  to  the 
early  summer  irrigation  so  necessary  for  producing  fruit  of  cannery 
grade,  chiefly  because  water  was  not  always  available  when  wanted. 
However,  the  standards  for  dried  fruit  are  constantly  being  raised 
and  the  larger  sizes  are  now  commanding  much  better  prices  than  the 
smaller.  The  tendency  is  to  follow  the  same  programme  of  irrigation 
for  all  apricots  whatever  the  purpose  for  which  they  are  used. 

For  best  results,  apricot  trees  should  be  irrigated  in  early  Sep- 
tember. However,  they  may  be  irrigated  a  little  earlier  or  a  little 
later.  In  no  case  should  fall  irrigation  be  postponed  until  after  the 
leaves  have  fallen.  The  purpose  of  fall  irrigation  is  to  enable  the 
trees  to  mature  a  supply  of  fruit  buds  for  next  year's  crop.  If  only 
a  light  winter  rainfall  is  to  be  expected,  there  is  no  harm  in  irrigating 
at  any  time  during  the  winter.  A  cheap  supply  of  water  is  often 
procurable  at  this  time,  but  it  should  be  clearly  understood  that  winter 
irrigation  is  merely  a  substitute  for  rainfall,  and  is  applied  in  the 
winter  rather  than  in  the  early  spring  only  for  convenience  or  economy. 
Apricot  trees  probably  cannot  form  fruit  buds  later  than  December 
for  the  next  season's  crop. 

A  favorite  method  of  irrigating  is  by  the  so-called  basin  or  check 
system  (fig.  8),  with  one  or  more  trees  to  a  check  or  basin.*  The 
levees  which  form  the  checks  may  be  made  with  a  disc,  with  a  ridger, 
or  even  with  a  two-horse  turning  plow.  Where  large  streams  of  water 
must  be  used,  which  necessitate  high  levees,  they  may  be  built  by 
plowing  usually  two  rounds  between  the  tree  rows  and  throwing  up 
the  levees  with  a  V.  Experience  is  required  to  learn  how  high  the 
levees  should  be  to  contain  enough  water  to  wet  the  ground  to  the 
required  depth. 

*For  methods  of  applying  water;  See  Farmers'  Bull.  No.  882,  tl Irrigation  of 
Orchards. ' ' 


30  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

By  the  check  method,  water  is  allowed  to  flow  from  one  check  to 
the  next,  the  levee  being  cut  when  the  upper  check  has  been  filled. 
By  the  basin  method,  a  supply  ditch  is  made  every  third  tree  row, 
each  basin  is  filled  to  the  top,  and  the  water  allowed  to  remain,  rather 
than  being  drawn  off  to  fill  the  next  basin.  Only  by  this  method  can 
a  definite  quantity  of  water  be  applied  to  each  tree.  It  would  be 
possible  to  improve  the  usual  check  method  by  filling  the  lowest  check 
in  the  tier  first  and  working  back  through  the  series  but  this  would 
necessitate  working  part  of  the  time  on  muddy  ground. 

The  furrow  system  of  irrigation  is  not  much  practiced  in  apricot 
orchards  in  the  northern  portion  of  the  state,  but  is  preferred  in  the 
south.  The  best  method  to  be  used  in  irrigating  an  orchard  is  that 
which  will  give  the  most  uniform  distribution  of  moisture  throughout 
the  soil.  This,  in  turn,  is  dependent  upon  the  available  head  of  water, 
the  soil  type,  the  topography  or  slope  of  the  land,  and  very  decidedly 
upon  the  care  with  which  the  land  has  been  graded  for  irrigation 
before  the  trees  were  planted.  It  is  impossible  to  secure  an  even 
irrigation  on  land  which  has  been  poorly  graded.  The  furrow  method 
of  irrigation  is  adapted  to  the  use  of  small  heads  of  water.  It  must 
be  used  if  the  irrigating  stream  is  very  small,  since  the  number  of 
furrows  in  which  the  water  is  running  at  any  time  can  be  reduced 
according  to  the  size  of  the  stream.  Furrows  may  be  used  on  a  wide 
range  of  slopes.  The  furrow  method  requires  less  moving  of  the 
surface  soil,  and  no  special  tools  are  required  to  prepare  the  orchard 
for  irrigation.  Much  less  labor  is  involved  in  irrigating  in  furrows 
than  in  basins  or  checks.  The  main  objection  to  this  method  is  that 
the  water  is  not  distributed  uniformly  through  the  soil,  and  it  is  almost 
impossible  to  wet  the  entire  soil  mass.  Improvement  can  be  made  on 
the  usual  practice  by  shortening  the  length  of  the  furrows  and  by  the 
use  of  a  greater  number  of  furrows  between  the  tree  rows. 

The  basin  method  is  best  adapted  to  relatively  flat  slopes  and  to 
large  heads  of  water.  Sandy  soils  on  flat  grades  should  always  be 
irrigated  by  this  method,  for  it  is  the  only  way  by  which  definite 
quantities  of  water  can  be  applied  to  each  tree.  The  use  of  furrows 
on  sandy  soil  usually  results  in  excessive  losses,  due  to  deep  percolation 
near  the  upper  ends  of  the  furrows.  The  basin  method  insures  an  even 
distribution  throughout  the  orchard.  Much  surface  soil,  however, 
must  be  moved  to  form  the  levees,  and  since  the  entire  surface  of  the 
soil  is  moistened,  the  loss  by  evaporation- is  greater  than  with  the 
furrow  method,  which  moistens  only  a  small  part  of  the  surface.  With 
this  method  constant  attention  is  required  to  turn  out  the  water  as 
each  basin  is  filled  and  there  is  a  tendency  to  puddle  and  bake  the  soil. 


Circular  238] 


THE    APRICOT    IN    CALIFORNIA 


31 


The  contour  method  of  irrigation  is  adapted  to  small  heads  of  water 
and  steep  grades.  Efficient  irrigation  on  the  steep  foothill  lands  can 
be  accomplished  only  by  contouring  the  orchard.  The  grade  or  slope 
of  the  tree  rows  depends  upon  the  ease  with  which  the  soil  erodes. 

The  only  way  to  determine  whether  the  orchard  has  been  wet  to  the 
proper  depth  is  to  explore  the  subsoil  with  a  soil  auger,  a  soil  tube,  or 
by  digging  a  few  holes.  It  is  advisable  for  the  beginner  to  apply  one 
of  these  tests  until  he  is  certain  that  he  knows  how  deep  a  given 


Fig.  8.  The  basin  method  of  irrigation  is  preferred  in  some  sections.  This 
method  insures  even  distribution  of  water  throughout  the  orchard,  and  enables 
the  grower  to  judge  how  much  water  each  tree  has  received. 

quantity  of  water  will  penetrate  his  soil.  After  the  spring  and  summer 
irrigations,  it  is  necessary  for  the  soil  to  be  wet  to  a  depth  of  five  or 
six  feet,  but  following  the  early  fall  watering,  the  soil  need  not  be 
wet  so  deep,  as  the  trees  will  be  able  to  set  a  good  crop  of  buds  and 
the  starting  of  the  cover  crop  will  be  assured  by  water  in  the  upper 
soil.  However,  a  light  fall  irrigation  is  based  on  the  belief  that  the 
winter  rainfall  will  be  sufficient  to  wet  down  to  a  depth  of  fully  six  feet. 


THINNING 

Apricots  are  thinned  to  secure  larger  size  and  to  prevent  loss  from 
rotting  at  ripening  time.  In  the  interior  valleys  there  is  not  likely 
to  be  much  injury  to  the  ripe  fruit  from  brown  rot,  but  it  may  be 


32  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

serious  in  the  coastal  region.  In  regions  where  fruit  is  grown  for  the 
cannery,  thinning  is  now  almost  universally  practiced.  Practically 
the  same  tonnage  can  be  produced  from  a  thinned  tree,  with  a  major 
portion  of  the  fruit  running  twelve  to  the  pound,  as  if  the  same  tree 
were  not  thinned,  with  perhaps  less  than  a  quarter  of  the  crop  coming 
within  the  twelve  grade,  the  remainder  running  perhaps  fifteen  to 
twenty  to  the  pound.  The  smallest  size  the  canneries  have  ever 
accepted  is  sixteen  to  the  pound.  Usually  only  twelve  are  accepted. 
Formerly  all  grades  of  dried  fruit  sold  for  practically  the  same  price, 
but  now  the  Prune  and  Apricot  Growers'  Association,  which  controls 
75  per  cent  of  the  apricot  acreage  of  the  state,  offers  a  premium  of 
several  cents  per  pound  for  the  larger  sizes. 

Thinning  should  be  done  about  the  middle  of  April  or  earlier,  before 
the  pits  become  hard.  In  the  absence  of  definite  experimental  data 
covering  the  subject,  it  may  be  advised  that  the  fruits  be  thinned  so 
that  they  do  not  touch  when  ripe.  Preferably  the  fruits  on  a  well- 
loaded  tree  should  be  four  or  five  inches  apart.  It  is  permissible  to 
leave  two  fruits  practically  opposite  each  other  on  a  twig  if  there  are 
no  others  within  four  inches.  It  is  not  profitable  to  try  to  thin  doubles, 
as  when  one  is  removed  the  other  is  so  badly  injured  it  is  likely  to 
drop  off.  Wherever  they  can  be  spared,  both  should  be  removed.  In 
sections  where  there  is  no  danger  of  brown  rot  attacking  the  ripe  fruit, 
clusters  of  three  or  even  four  fruits  may  be  left,  especially  on  young 
trees,  where  not  much  would  remain  if  clusters  were  rigidly  thinned 
according  to  the  rules  given  above.  Along  the  coast  it  is  never  advis- 
able to  leave  clusters.  Enough  moisture  from  the  damp  air  at  night 
is  held  between  the  fruits  that  touch  to  permit  the  brown-rot  spores 
to  germinate.  At  present  no  sprays  are  known  that  can  be  safely 
applied  to  apricot  trees  in  summer  as  a  protection  against  the  brown 
rot  on  the  ripe  fruit. 


SPRAYING 

Apricot  diseases  controlled  by  spraying  in  California  are  shothole 
fungus  and  brown  rot.  Other  diseases,  such  as  scab  (Cladiosporum 
carpophilum)  and  blossom  or  jacket  rot  (Slerotinia  libertiana), 
especially  the  latter,  may  cause  more  or  less  trouble  in  certain  years. 
These  are  only  partially  controlled  by  spraying.  Serious  diseases  that 
cannot  be  controlled  by  spraying  are :  oak  root  fungus,  bacterial 
gummosis,  black  heart,  and  crown  gall.  The  physiological  trouble 
known  as  sour  sap  may  also  be  included  in  this  list. 


Circular  238]  THe  APRICOT  IN  CALIFORNIA  33 

The  principal  insects  combated  by  spraying  are :  brown  scale,  black 
scale,  and  twig  borer.  Leaf-eating  insects  like  caterpillars  may  be 
poisoned  with  arsenical  sprays,  but  other  methods  of  eradication  (such 
as  burning  with  a  torch)  are  generally  employed.  Spraying  is  not 
effective  against  borers  attacking  trunk  and  roots. 

Shothole  Fungus  (Corynemn  beijernickii  Oudem). — This  disease 
attacks  the  fruit,  leaves,  and  twigs,  and  is  the  same  fungus  that  causes 
the  peach  twig  blight.  In  the  apricot,  the  disease  is  characterized  by 
spotting  of  the  fruit,  perforation  of  the  leaves,  and  killing  of  the 
winter  buds.  The  tender  growing  twigs  may  be  attacked  in  spring, 
causing  the  tips  to  die  back  for  several  inches.  The  fruiting  twigs  are 
not  so  liable  to  be  affected  as  the  new  ones  that  are  only  a  few  weeks 
old.  The  diseased  fruit  does  not  rot,  but  the  scabby  condition  of  the 
skin  makes  it  unfit  for  canning  and,  if  severe,  may  ruin  or  lower  its 
value  for  drying.  The  leaves  may  be  so  badly  perforated  as  to  make 
the  tree  look  as  if  they  had  been  fired  on  with  a  shotgun,  hence  the 
name. 

The  fungus  becomes  active  in  the  fall  after  one  or  two  good  rains 
have  moistened  the  soil  and  rendered  the  air  humid.  Spraying  at  this 
time  is  most  important.  During  the  winter  the  fungus  works  in  the 
buds,  and  they  may  fail  to  open  in  the  spring.  All  the  buds  on  a 
single  twig  may  be  destroyed  in  this  way,  often  the  twig  itself  killed. 
On  such  twigs  there  is  little  or  no  surface  indication  of  the  fungus, 
although  upon  close  examination  the  spores  may  be  found  in  abundance 
among  the  bud  scales.  Occasionally  there  may  be  a  slight  gumming 
noticed  on  the  dormant  twigs,  especially  around  the  buds.  There  is 
a  very  pronounced  gumming  of  the  young  growing  twigs  when  attacked 
in  spring.  This  is  especially  true  of  the  young  twigs  that  are  produced 
the  same  spring  they  are  attacked.  The  presence  of  gum  is  often 
mistaken  for  the  work  of  brown  rot. 

Shothole  fungus  is  the  worst  disease  of  the  interior  valley  sections 
of  the  state.  It  is  rarely  seen  on  apricots  along  the  coast,  although 
occasionally  it  may  be  severe  enough  to  make  spraying  necessary.  It 
may  be  controlled  by  spraying  the  trees  both  in  fall  and  spring  with 
Bordeaux  4-5-50,  lime-sulphur  1-10,  or  dry  lime-sulphur  12-50.  The 
fall  spraying  should  be  done  in  November  or  early  December  after  the 
rains  have  commenced,  and  the  spring  spraying  after  the  buds,  are 
noticeably  swollen.  The  latter  application,  if  delayed  until  the 
blossoms  are  beginning  to  open,  will  also  serve  as  a  protection  against 
brown  rot,  and,  if  lime-sulphur  is  used,  will  in  addition  kill  any  twig 
borers  that  may  be  present. 


34  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

Brown  Kot  (Sclcrotinia  cinerea  (Bon.)  Wor.). — Brown  rot  is  the 
worst  disease  of  the  coastal  region,  and  seems  to  be  on  the  increase, 
not  only  along  the  coast,  but  in  rather  remote  coastal  valleys  and  for 
almost  a  hundred  miles  up  the  Sacramento  River.  Both  fruit  and 
flowers  are  attacked.  The  most  damage  is  done  by  killing  the  blossoms 
and  quickly  spreading  and  killing  the  fruiting  spurs.  Infection  appar- 
ently occurs  when  the  trees  are  in  bloom  or  slightly  before.  The 
diseased  twigs  are  characterized  by  severe  gumming.  Masses  of  gum 
are  always  found  on  the  twigs  at  the  point  where  the  disease  stopped 
advancing.  The  fungus  appears  to  work  with  great  difficulty  in  wood 
that  is  more  than  a  year  old.  Large  masses  of  gum,  showing  the 
presence  of  the  disease,  are  often  noticed  on  branches  three  or  four 
years  old  or  older,  but  upon  close  examination  it  is  observed  that  the 
parasite  has  gained  entrance  to  the  older  wood  through  the  medium 
of  a  short  spur.  Infection  does  not  take  place  through  the  bark  unless 
an  insect  wound  or  abrasion  is  present. 

Brown  rot  may  also  cause  considerable  injury  by  attacking  the 
fruit  at  or  near  ripening  time.  Where  the  apricots  are  growing  in 
clusters,  they  quickly  rot,  and  the  whole  mass  will  be  found  glued 
together.  Masses  of  fruit  may  rot  when  single  specimens  escape,  hence 
the  necessity  for  thinning  so  that  the  individual  fruits  do  not  touch. 
Apricots  that  have  rotted  are  apt  to  dry  up  and  hang  on  the  trees.  It 
is  these  mummies  that  are  chiefly  responsible  for  carrying  the  disease 
over  winter.  Every  specimen  will  be  found  to  be  covered  with  pustules 
containing  thousands  of  spores.  Decayed  fruit  allowed  to  remain  on 
the  ground  becomes  as  great  a  menace  as  the  mummies  on  the  trees. 
All  decayed  fruit  should  be  buried,  and  each  mummy  should  be  care- 
fully picked  from  the  tree  and  either  buried  or  burned.  Plowing  the 
mummies  under  is  not  a  good  practice,  as  they  are  likely  to  be  brought 
to  the  surface  again  by  cultivation. 

As  many  of  the  diseased  twigs  as  possible  should  be  removed  from 
the  trees  when  the  latter  are  pruned  during  the  winter,  because  these 
twigs  serve  as  sources  of  infection  in  the  spring.  It  may  be  a  practical 
impossibility  to  cut  out  all  of  the  diseased  parts,  especially  where  the 
fungus  has  gained  entrance  to  the  older  wood  through  small  spurs. 
Some  prefer  to  cut  out  the  diseased  twigs  during  the  early  summer, 
when  they  can  best  be  seen  by  contrast  with  the  living  twigs.  It  is 
more  expensive  to  cut  them  out  in  summer,  and  it  is  very  doubtful  if 
their  removal  at  this  time  will  have  any  appreciable  effect  in  protecting 
the  ripe  fruit  from  being  attacked.  No  spray  treatment  has  yet  been 
devised   for   preventing  the   disease    from   attacking  the    ripe    fruit. 


Circular  238]  the  apricot  in  CALIFORNIA  35 

Sulphur  sprays  apparently  cannot  be  used  with  safety  on  apricot  trees 
after  the  fruit  has  set,  on  account  of  injury  to  the  fruit  itself,  as  well 
as  to  the  leaves.  Other  standard  sprays,  when  used  at  fungicidal 
strength  in  summer,  are  also  apt  to  injure  the  apricot  leaves. 

Spraying  in  spring  to  control  brown  rot  gave  good  results  in  1920, 
especially  when  lime-sulphur  or  Bordeaux,  used  at  winter  strength, 
was  applied  quite  near  the  blooming  time.  Results  of  experiments 
that  spring  indicated  that  the  nearer  the  trees  were  in  bloom  when  the 
spraying  was  done,  the  better  would  be  the  protection  against  the 
disease.  These  results  were  borne  out  by  experiments  and  experience 
of  growers  in  1921.  However,  apparently  on  account  of  peculiar 
wreather  conditions,  the  protection  from  spraying  in  1921  was  not  so 
good  as  that  of  the  year  before.  Still,  the  spraying  was  on  the  whole 
a  profitable  investment.  There  is  some  indication  that  the  results  of 
spraying  are  cumulative,  that  is,  that  the  disease  can  best  be  held  in 
check  when  the  same  trees  are  sprayed  year  after  year.  There  are  also 
reasons,  indicated  by  results  obtained  in  1921,  for  believing  that  a 
winter  spray,  applied  as  late  as  January,  will  help,  particularly  in 
badly  infected  orchards,  if  followed  by  the  spring  spray  as  the  trees 
are  coming  into  bloom. 

The  spray  treatment  that  can  be  most  recommended  at  the  present 
time  is  to  use  either  Bordeaux  mixture  4-5-50  or  lime-sulphur  1-10, 
or  dry  lime-sulphur  12-50  at  the  time  a  few  blossoms  are  open  and  the 
remainder  are  in  full  pink  stage.  Ordinarily  it  is  not  safe  to  wait 
until  full  bloom,  because  of  danger  of  very  severe  infection  if  the  open 
blossoms  are  moistened  by  fog  or  spring  rains  before  the  application 
of  the  spray.  Spraying  after  the  blossoms  begin  to  wilt  is  not  only 
useless  but  dangerous;  it  is  too  late  to  protect  against  infection,  and 
sulphur  sprays  are  liable  to  injure  the  fruit  immediately  after  it  sets 
or  later.  Bordeaux  sprays,  even  of  summer  strength,  applied  when 
the  blossoms  are  falling  may  not  injure  the  fruit,  but  they  may  burn 
the  foliage  severely.  The  amount  of  spray  injury  of  this  kind  is 
usually  greater  when  the  moisture  content  of  the  air  is  high. 

Oak  Fungus  (Armillaria  mellea) . — Oak  fungus  is  common  on  all 
deciduous  fruit  trees  except  figs,  pears  on  French  stock,  and  walnuts  on 
Northern  California  Black  "Walnut  stock.  The  disease  will  attack 
apricot  trees  on  any  root  stock  on  which  they  may  be  grown.  The 
disease  can  live  on  either  living  or  dead  wood.  It  spreads  from  tree 
to  tree  by  following  the  roots.  In  many  sections  of  California,  oak 
fungus  has  existed  along  with  the  wild  vegetation,  being  especially 
prevalent  on  the  roots  of  oak  trees,  hence  the  name.     If  any  of  the 


36  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

diseased  roots  of  a  tree  are  left  in  the  ground,  the  fungus  will  remain 
alive  until  the  roots  decay.  In  this  way  fruit  trees,  even  in  fairly  old 
orchards,  suddenly  contract  the  disease  in  a  spot  where  it  was  not 
known  to  exist  before.  This  is  especially  true  of  places  where  oak 
trees  were  abundant.  Oak  roots  in  an  arid  region  may  remain  in  the 
soil  for  twenty  or  thirty  years  before  decaying.  There  is  reason  for 
believing  that  where  an  orchard  is  irrigated  once  or  twice  during  the 
summer  the  rate  of  decay  will  be  much  more  rapid. 

Oak  fungus  is  characterized  by  the  white  color  and  fanlike  designs 
on  the  inner  bark,  and  the  peculiar  mushroom  odor  of  the  diseased 
parts.  Where  only  one  root  of  an  apricot  tree  is  affected,  and  where 
the  disease  may  have  reached  the  crown  of  the  tree,  there  is  consider- 
able gumming  on  the  trunk  on  the  affected  side.  This  gum  exudation 
from  the  healthy  bark  a  foot  or  so  from  the  ground  may  be  seen  even 
before  the  branch  on  that  side  begins  to  show  distress.  In  this  early 
stage,  it  is  possible  to  save  the  tree  by  cutting  out  the  diseased  part 
and  disinfecting  the  wound.  To  be  absolutely  safe,  it  is  necessary  to 
dig  up  all  the  diseased  roots,  to  prevent  healthy  ones  from  coming  in 
contact  with  them.  The  presence  of  the  fungus  is  indicated  in  early 
winter  by  masses  of  toadstools  which  come  up  from  the  base  of  the 
tree.  These  toadstools,  or  more  properly  mushrooms,  are  edible, 
especially  when  they  first  come  up.  There  is  little  to  be  gained  by 
destroying  these  mushrooms,  as  it  is  not  believed  that  the  disease 
spreads  from  the  spores,  but  from  the  mycelial  growth  in  the  roots,  or 
from  the  rhyzomorphs,  which  are  masses  of  fungus  threads  enclosed 
in  a  brownish  covering,  and  which  are  capable  of  reaching  out  into  the 
soil  for  two  or  three  feet.  If  they  come  in  contact  with  the  root  of 
another  tree,  they  immediately  attack  it.  Usually  the  roots  of  healthy 
trees  sooner  or  later  come  into  contact  with  diseased  roots  from  an 
adjoining  tree,  and  thus  contract  the  disease.  When  a  tree  is  attacked, 
the  disease  generally  spreads  in  all  directions.  Armillaria  spots  are 
therefore  usually  circular  in  shape,  and  additional  trees  around  the 
border  of  such  spots  continue  to  die  each  year. 

The  only  known  remedy  for  oak  fungus  is  to  construct  barriers 
around  diseased  spots  so  that  the  roots  of  healthy  trees  cannot  invade 
the  diseased  area.  Perhaps  the  most  effective  barrier  would  be  a 
concrete  wall  four  inches  thick,  extending  down  as  deep  as  the  roots 
penetrate,  which  would  be  from  3%  to  61/o  feet,  according  to  the 
character  of  the  soil.  The  walls  should  not  come  so  near  the  surface 
as  to  interfere  with  plowing  or  cultivation.  By  practicing  heavy 
irrigation,  the  dead  apricot  roots  may  be  caused  to  decay  in  four  or 


Circular  238]  the  apricot  IN  California  37 

five  years.  Kather  than  leave  the  ground  bare  where  two  or  three  or 
half  a  dozen  trees  have  died,  and  where  the  area  has  been  walled  in, 
apricots  may  be  replanted  by  first  opening  out  holes  eight  to  ten  feet 
wide  and  at  least  three  feet  deep.  All  fragments  of  roots  may  be 
spread  on  the  ground.  The  disease  will  die  after  an  exposure  of  a 
week  or  two  to  the  summer  sun.  The  holes  may  be  filled  with  fresh 
soil,  and  there  is  a  chance  that  the  old  diseased  roots  may  decay  before 
the  roots  of  the  replanted  trees  come  in  contact  with  them.  There  is 
no  assurance,  however,  that  replanted  apricots  will  not  contract  the 
disease  within  a  few  years.  The  only  safe  plan  is  to  replant  with 
pears  or  walnuts,  or  to  use  the  land  for  garden  purposes  or  alfalfa. 

Bacterial  Gummosis  (Pseudomonas  cerastes  Griffin). — This  disease 
is  new  in  California,  having  been  serious  on  apricots  only  during  the 
last  three  or  four  years.  On  young  or  old  trees,  the  disease  is  mani- 
fested by  copious  gumming.  The  masses  of  gum  may  be  light  amber 
in  color,  but  as  a  rule  they  are  of  a  decidedly  yellowish  tinge,  and  the 
typical  color  is  a  pale  yellow.  The  typical  gum  mass  caused  by 
gummosis  is  quite  opaque,  while  masses  of  gum  produced  from  other 
causes  are  transparent.  The  final  test  of  gummosis  is  the  pocket  or 
cavity  beneath  the  bark,  which  is  filled  with  a  pus-like  material,  at 
least  when  the  disease  is  active.  On  old  cherry  trees  the  pus  pockets 
sometimes  occur  between  the  inner  and  outer  layers  of  the  bark.  The 
"pus"  seems  to  collect  in  the  cavities,  and  there  may  be  a  noticeable 
swelling  of  the  bark  until  the  latter  breaks  and  allows  the  contents 
of  the  pockets  to  ooze  out.  Apparently  the  mechanical  injury  to  the 
bark  in  the  vicinity  of  the  pockets  may  sometimes  cause  a  certain 
amount  of  gumming,  but  this  gum  will  be  amber- colored  and  trans- 
parent. 

Gummosis  will  kill  apricot  trees  from  one  to  three  years  old, 
usually  the  year  they  are  attacked,  while  old  trees  may  survive  for 
several  years.  Although  the  disease  is  usually  confined  to  the  trunk 
and  branches,  it  may  occur  even  in  the  one  and  two-year-old  twigs. 
It  is  most  active  during  the  winter  months,  but  may  be  active  in  the 
spring  as  late  as  April  or  May,  especially  in  the  cooler  regions  along 
the  coast. 

Gummosis,  being  a  bacterial  disease,  is  readily  spread  by  pruning 
tools.  Pruners  should  be  taught  to  recognize  the  disease,  and  in  prun- 
ing affected  trees  they  should  be  provided  with  a  supply  of  bichlorid 
of  mercury  for  disinfecting  their  shears  or  saws  after  cutting  into  the 
diseased  parts.  The  treatment  for  bacterial  gummosis  is  to  cut  out  all 
of  the  diseased  parts  of  the  bark,  scrape  the  wood,  and  then  apply  a 


38  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

1-500  solution  of  bichloride  of  mercury  or  mercury  cyanide.  After 
the  wound  dries,  it  should  be  thoroughly  painted  with  Oronite.  If 
taken  in  time,  diseased  trees  can  easily  be  saved  by  this  cutting-out 
method.  However,  young  trees  are  likely  to  be  killed  before  the 
disease  is  noticed. 

Black  Heart  (VerticilUum  sp.). — This  is  an  obscure  disease  which 
causes  apricot  branches  to  die,  usually  in  early  summer.  It  is  generally 
worst  in  trees  from  three  to  five  years  old,  although  it  may  occur  in 
much  older  trees.  In  May  or  June  the  leaves  on  an  affected  branch, 
particularly  toward  the  tip,  suddenly  collapse,  and  they  may  be  seen 
to  be  wilted  at  points  lower  down.  On  cutting  off  such  branches,  it  is 
found  either  that  the  entire  heart  wood  is  black,  or  that  an  outer  ring 
of  the  heart  is  darker  than  the  remainder.  In  many  instances,  black 
heart  seems  to  be  associated  with  excessive  irrigation,  especially  during 
the  first  year  or  two  the  trees  are  in  the  orchard.  A  great  deal  of  black 
heart  has  been  observed  in  orchards  where  strawberries  or  tomatoes 
were  grown  between  the  tree  rows.  Both  these  crops  are  usually 
irrigated  several  times  during  the  season,  and  the  watering  is  continued 
almost  until  the  first  frost  comes.  Black  heart  has  also  been  observed 
to  occur  on  two  or  three-year-old  trees  where  no  irrigation  has  been 
practiced. 

The  disease  is  caused  by  a  fungus,  and  infection  seems  to  come  from 
the  soil.  No  satisfactory  treatment  is  known.  In  the  past,  growers 
have  been  advised  to  cut  back  the  diseased  parts  to  healthy  wood,  or 
even  to  dig  up  the  trees.  While  cutting  back  the  trees  may  not  stop 
the  disease  or  prevent  its  recurrence,  the  removal  of  dead  branches 
can  do  no  harm,  and  greatly  improves  the  appearance  of  the  trees. 
Trees  have  sometimes  been  observed  to  make  a  complete  recovery  after 
a  year  or  two.  On  the  other  hand,  the  disease  has  been  known  to 
recur  in  trees  the  following  year  after  diseased  parts  were  cut  out.  On 
the  whole,  it  is  better  to  cut  back  to  healthy  wood  and  give  the  trees  a 
chance  to  recover. 

Crown  Gall  (Bacterium  tumefaciens) . — This  is  an  old  disease  that 
causes  characteristic  warts  or  galls  on  the  crown  or  roots  of  the  trees. 
It  is  worse  on  almond  or  peach  stock  than  on  myrobalan  or  apricot. 
The  disease  rarely  kills  a  tree,  but  may  be  one  of  the  factors  which 
reduces  the  vitality.  The  crown  gall  does  the  most  harm  after  it  has 
encircled  the  crown.  It  is  apt  to  be  worst  when  borers  are  prevalent. 
The  galls  make  good  hiding  places  for  the  borers,  and  the  latter 
undoubtedly  spread  the  infection. 

If  the  galls  are  noticed  when  small,  or  considerably  before  they 
have  encircled  the  tree,  they  may  be  chiseled  off  and  the  wounds 


Circular  238]  THE  APRIC0T  IN  CALIFORNIA  39 

painted  with  a  concentrated  solution  of  copper  sulphate  (bluestone). 
The  wounds  should  then  be  sealed  with  Oronite. 

Sour  Sap. — Sour  sap  does  not  seem  to  be  caused  primarily  by  a 
fungus  or  a  bacterium.  It  is  most  common  in  young  trees.  It  most 
frequently  occurs  where  the  roots  of  the  trees  are  "water-logged"  in 
winter,  which  may  occur  if  the  subsoil  is  heavy  and  not  well  drained. 
It  also  occurs  in  gravelly  spots  where  the  soil  is  subject  to  extremes  of 
moisture  and  of  temperature.  Sour  sap  is  usually  most  prevalent  on 
the  sunny  side  of  the  trunk,  but  in  severe  cases  the  entire  tree  may 
become  involved.  This  trouble  may  be  recognized  by  the  characteristic 
odor  caused  by  fermentation  of  the  sap  in  the  affected  parts  of  the  tree. 

Apparently  the  most  direct  cause  of  sour  sap  is  extremes  of  tem- 
perature in  late  winter  or  early  spring.  The  tissues  of  the  trees  may 
become  active  on  warm,  sunny  days,  thus  rendering  them  susceptible 
to  injury  from  low  temperatures  which  may  follow.  Trees  grown  in 
soils  subject  to  extremes  of  moisture  and  of  temperature  are  liable  to 
make  intermittent  growth.  They  are  especially  liable  to  make  a  soft, 
succulent  growth  in  late  fall,  just  when  they  should  be  "ripening" 
their  wood  and  storing  plant  food  reserves  for  winter.  Such  trees 
have  a  less  definite  winter  rest.  They  are  more  liable  to  be  awakened 
into  activity  on  sunny  days  in  late  winter  or  spring  and  more  subject 
to  injury  from  subsequent  cold  spells.  On  the  other  hand,  trees  are 
less  susceptible  to  sour  sap  if  they  make  uninterrupted  seasonal 
growth ;  cease  length  growth  in  early  autumn,  ripen  their  wood  and 
store  plant  food  reserves  for  winter.  Such  trees  have  a  more  definite 
winter  rest,  they  are  less  liable  to  be  forced  into  activity  or  growth  on 
sunny  winter  days  and  are  more  resistant  to  subsequent  cold  spells. 

Treatments  which  oppose  sour  sap  are  possible.  If  there  is  an 
impervious  layer  of  hard  pan,  not  far  below  the  surface,  it  should  be 
broken  by  subsoiling  or  by  the  use  of  dynamite  to  afford  drainage  into 
the  pervious  subsoil  beneath.  If  dynamite  is  used,  the  work  should  be 
done  when  the  subsoil  is  dry  enough  to  avoid  "puddling."  On  poorly 
drained  soils  a  furrow  may  be  opened  on  each  side  of  the  tree  row  in 
the  fall  to  carry  off  surface  water  during  heavy,  winter  rains.  Low 
places  in  the  orchard  where  winter  water  stands,  should  be  drained 
by  means  of  furrows  leading  to  a  convenient  outlet. 

Gravelly  spots  in  the  orchard  should  not  be  allowed  to  dry  out 
unduly  in  summer.  Such  areas  may  be  irrigated  more  frequently  or 
more  abundantly  if  conditions  admit.  Moisture  may  be  conserved  by 
tillage  and  keeping  down  weeds  during  summer.  Manure  applied  to 
dry  spots  will  further  conserve  soil  moisture.     Where  winter  rainfall 


40  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

is  low,  proper  contouring  about  trees  on  dry  spots  may  catch  winter 
run- off  and  conserve  it  in  the  soil. 

Sour  sap  is  also  opposed  by  whitewashing  young  trees  during 
December.  The  wash  should  be  reapplied,  if  necessary,  to  retain  a  white 
cover  until  spring.  The  whitewash  reflects  the  heat  on  sunny  winter 
days  and  prolongs  the  rest  period  of  the  trees.  Whitewash  on  the 
trunk  should  extend  a  few  inches  below  ground,  since  the  growing 
layer  of  the  tree  gets  hottest  at  the  surface  of  the  dark  soil,  where  the 
most  heat  is  absorbed.  The  coloring  matter  in  the  bark  of  young  trees 
frequently  absorbs  heat  enough  on  sunny  winter  days  to  raise  the 
temperature  of  the  growing  layer  25°  to  30°  F.  above  the  temperature 
of  the  air.  The  whitewash  reflects  the  heat,  so  the  tree  remains  at 
atmospheric  temperature  or  even  a  few  degrees  lower. 

In  selecting  nursery  stock  to  plant  on  soils  where  sour  sap  is  likely 
to  occur,  it  is  safest  to  choose  trees  that  ceased  length  growth  moder- 
ately early  and  perfected  their  growth  for  winter,  rather  than  trees 
which  grew  unduly  late  in  the  fall. 

Death  of  young  trees,  due  to  bacterial  gummosis  or  other  causes,  is 
often  termed  sour  sap. 

Green  Rot  (Sclerotinia  libertiana) . — This  is  known  also  as  blossom 
or  calyx  rot  and  sometimes  jacket  rot.  The  disease  attacks  the  green 
fruit  a  week  or  two  after  the  blossoms  fall,  when  there  is  much  fog  or 
rainy  weather.  Apparently  the  spores  find  lodgment  beneath  the 
"  jackets, "  and  the  moisture  enables  them  to  germinate  and  grow. 
Spots  appear  on  the  little  apricots,  and  sometimes  the  blossom-end  or 
one  whole  side  decays.  The  fruit  soon  drops.  Green  rot  does  not 
appear  some  years,  but  is  of  considerable  economic  importance  during 
seasons  when  weather  conditions  favor  its  development. 

No  separate  spray  treatment  has  been  worked  out  for  this  disease. 
Probably  the  spray  programme  used  against  brown  rot  will  be  as 
effective  as  any  treatment  that  could  be  suggested. 


INSECTS 

Brown  Scale  (Lecanium  comi  Bouche). — This  insect  is  also  known 
as  the  European  Fruit  Lecanium.  The  chief  injury  to  apricots  is  an 
indirect  one.  The  insects  excrete  a  honeydew  which  covers  the  leaves 
and  fruit,  and  a  sooty  mold  grows  abundantly  in  this  honeydew  and 
gives  a  blackened  appearance  to  the  fruit,  causing  it  to  be  rejected  by 
the  canneries.  Such  fruit  can  be  saved  by  drying,  but  it  does  not  make 
a  fancy  product. 


Circular  238]  THE  apricot  in  CALIFORNIA  41 

The  brown  scale  ranges  in  color  from  amber  to  a  dark  reddish 
brown.  The  insects  are  about  one-eighth  of  an  inch  long.  The  eggs 
are  very  small,  slightly  oblong,  and  pearly  white.  The  young  are 
light  yellow,  turning  a  reddish  brown  as  they  grow  older.  The  eggs 
are  laid  in  April  and  May.  Upon  hatching,  the  young  settle  upon  the 
leaves  and  younger  twigs,  where  they  remain  during  the  summer. 
During  the  winter  they  are  in  a  half-grown  stage.  Severe  infestations 
occur  only  periodically.     There  is  but  one  brood  a  year. 

Brown  scale  is  very  common  throughout  the  state,  but  is  worst 
along  the  coast,  especially  in  the  Santa  Clara  Valley  section.  It  may 
be  controlled  by  spraying  the  dormant  trees  with  crude  oil  emulsion, 
distillate  emulsion,  or  a  miscible  oil.  Preferrably,  spraying  should  be 
done  during  January  and  February.*  One  thorough  spraying  every 
two  or  three  years  should  be  sufficient. 

Black  Scale  (Saissetia  oleae). — The  occurrence  and  habits  of  the 
black  scale  are  very  similar  to  those  of  the  brown  apricot  scale,  and 
the  same  remedial  measures  will  apply,  especially  the  use  of  miscible 
oils  and  distillate  emulsions. 

Twig  Borer  (Anarsia  lineatella  Zeller). — This  insect  is  generally 
known  as  the  peach  twig  borer,  as  it  was  first  observed  to  occur  in 
peach  trees  and  has  only  lately  spread  to  apricots.  The  insects  attack 
both  the  young  growing  twigs  and  the  fruit.  The  larvae  or  worms 
winter  over  in  small  chambers  made  just  beneath  the  bark  in  the 
crotches,  being  found  most  commonly  where  branches  are  from  one 
and  a  half  to  two  inches  in  diameter.  They  may  be  located  by  the 
small  chimneys  of  frass  pushed  out  in  the  process  of  making  the 
burrows.  As  the  leaf  buds  begin  to  open  in  spring,  the  insects  crawl 
out  and  begin  to  feed.  They  start  in  the  leaf  axils  near  the  tips  of 
the  twigs  and  bore  down  the  center  of  the  stem,  thus  killing  the  tips. 
By  May  they  are  mostly  full-grown.  They  conceal  themselves  in 
crevices  in  the  bark  and  within  one  or  two  weeks  emerge  as  adult 
moths,  steel-gray  in  color,  and  about  one-half  inch  from  tip  to  tip 
when  the  wings  are  spread.  Not  all  of  the  larvae  become  full-grown 
by  May,  and  the  later  maturing  individuals  of  the  first  brood  attack  the 
fruit  just  as  it  is  beginning  to  ripen  in  June  or  July.  The  moths 
immediately  begin  to  lay  eggs,  and  when  the  young  of  the  second 
generation  have  hatched  out,  instead  of  attacking  the  fruit,  as  is 
generally  supposed,  they  begin  at  once  to  construct  their  hiding  places, 
where  they  remain  throughout  the  rest  of  the  summer  and  over  winter. 


*  See    Univ.    Calif.    Circ.    224,    "Control    of    the    Brown    Apricot    Scale    on 
Deciduous  Fruit  Trees." 


42  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

The  twig  borer  may  do  very  serious  injury  to  apricot  trees  one  and 
two  years  old  by  destroying  the  tips  of  the  branches,  thus  making  it 
impossible  to  grow  shapely  trees.  The  injury  may  be  so  severe  on 
either  young  or  old  trees  as  to  cause  them  to  be  seriously  weakened. 
Fortunately,  control  measures  are  simple  and  unusually  effective.  The 
standard  treatment  is  to  spray  the  trees  with  lime-sulphur  1-10  as 
the  buds  begin  to  show  signs  of  opening  in  spring.  On  bearing  trees, 
the  treatment  may  be  delayed  until  the  trees  are  coming  into  bloom, 
when  the  spray  will  also  serve  as  a  treatment  against  brown  rot.  In 
certain  sections,  the  twig  borer  does  much  harm  by  causing  the 
apricots  to  be  wormy. 

California  Peach  Borer  (Mgeria  opalescens) . — This  borer  usually 
attacks  the  trees  just  beneath  the  surface  of  the  ground,  although  they 
may  be  found  at  the  surface  or  even  a  few  inches  above.  Borers  of 
this  kind  are  found  in  California  only  along  the  coast,  where  they 
often  becomes  a  serious  pest  of  all  stone  fruits.  More  damage  is  done 
where  apricots  are  growing  on  peach  root  than  on  either  apricot  or 
myrobalan. 

Borers  should  be  thoroughly  dug  out  in  the  fall  or  winter,  and 
the  wounds  sealed  up  with  hard  asphaltum  of  the  grade  known  as 
S-Flotine.  This  must  be  applied  hot.  Roofing  paint  known  as  Oronite 
may  be  used.  The  latter  is  cheap  and  can  be  applied  cold.  It  is  a 
good  plan  to  apply  a  heavy  coating  of  cne  of  these  materials  over  the 
entire  crown  of  the  trees  from  six  to  eight  inches  below  ground  (down 
to  the  main  roots)  to  four  or  five  inches  above  ground.  The  Oronite 
requires  renewal  every  year,  while  the  asphaltum  usually  lasts  two 
years. 

The  parent  of  the  borer,  a  wasp-like  moth,  lays  its  eggs  on  the 
lower  part  of  the  trunks  of  the  trees  from  April  to  June,  and  these 
hatch  in  from  fifteen  to  thirty  days.  The  borers,  when  very  small,  seek 
shelter  in  the  crevices  of  the  bark  and  begin  at  once  to  bore  their  way 
into  the  wood.  During  the  summer  they  work  upon  the  growing  inner 
bark,  burrowing  upward  or  downward  at  will.  The  frass,  and  also 
gum,  is  forced  out  of  the  exit  holes  through  the  side  of  the  trees.  The 
borers  remain  in  the  burrows  during  the  winter  months,  and  continue 
fairly  active.  In  January  or  February,  they  transform  into  pupae. 
These  remain  in  the  old  burrows  for  about  one  and  one-half  months, 
when  they  emerge  as  full-grown  moths,  which  shortly  begin  to  lay  eggs. 
There  is  but  one  generation  a  year. 

The  Flat-headed  Apple  Tree  Borer  (Chrysobothris  femorata). — 
This  insect  is  apt  to  attack  any  young  tree  that  has  become  weakened 


Circular  238]  THe  apricot  in  California  43 

from  any  cause,  but  especially  from  sunburn.  Healthy  trees  with  a 
full  sap  flow  are  very  rarely  attacked.  .The  borers  work  on  the  trunks, 
usually  six  to  twelve  inches  from  the  ground.  They  do  a  great  deal 
of  harm  in  the  interior  valleys  and  adjacent  foothill  sections.  Only 
rarely  do  they  occur  along  the  coast. 

The  parent  of  the  flat-headed  borer  is  an  oblong,  flattened,  and 
metallic  greenish-black  or  grayish  beetle.  The  females  are  about  one- 
half  inch  long.  The  borers  are  white  or  yellow,  and  from  one-half 
to  three-fourths  of  an  inch  long.  The  head  end  is  greatly  enlarged  and 
flattened,  so  that  the  burrows  they  make  are  elliptical  in  shape.  In  a 
few  weeks  they  will  completely  girdle  a  young  tree. 

The  eggs  are  laid  in  early  spring  under  any  loose  scales  of  bark  or 
in  crevices.  After  hatching,  the  borers,  which  are  very  small  at  first, 
bore  into  the  sapwood  upon  which  they  feed.  Later  they  work  into  the 
older  and  firmer  wood.  Finally  they  work  outward  nearly  through  the 
bark,  form  large  cells,  and  go  into  the  pupal  stage.  In  the  spring 
they  emerge  as  full-grown  flying  beetles,  ready  to  begin  egg-laying. 
Both  young  and  old  trees  are  attacked,  the  latter  often  in  the  branches 
if  they  are  sunburned. 

Control  measures  consist  in  prevention.  Whitewash  or  shade  the 
trunks  of  young  trees  to  prevent  sunburn,  and  do  not  open  up  large 
holes  in  the  tops  of  the  trees  in  pruning.  Keep  all  trees  growing 
steadily  and  flat-headed  borers  will  pass  them  by. 


FEOST  FIGHTING 

On  account  of  its  early  blooming  habit,  the  apricot  is  apt  to  be 
injured  by  spring  frosts.  Experience  has  shown  that  an  ordinary  frost 
at  blossoming  time  may  be  successfully  combated  by  heating  the  air  of 
the  orchard.  The  cost  is  small  compared  with  the  value  of  the  crop. 
The  heating  is  done  by  burning  stove  distillate  or  crude  oil  in  pots 
or  heaters  made  for  the  purpose.  The  object  of  using  heaters  is  to 
add  enough  heat  to  the  air  to  prevent  the  temperature  from  falling 
below  the  critical  point.    Smoke  is  of  but  little  value. 

The  so-called  "lardpail"  or  open  type  of  pot  or  heater  is  the  one 
in  most  common  use,  although  some  orchardists  are  installing  the 
improved  stack  type.  The  one-gallon  open  type  with  flame  deflector 
costs  from  30  cents  to  35  cents  and  will  burn  for  approximately  two 
hours.  The  two-gallon  size  with  deflector  costs  about  45  cents  and 
burns  for  approximately  four  hours.  In  a  few  cases,  growers  have 
used  tin  cans,  size  number  10,  with  a  fair  degree  of  success. 


44  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

From  seventy-five  to  one  hundred  heaters  of  the  open  type  are 
required  per  acre.  A  smaller  number  of  the  stack  type  are  sufficient. 
When  the  small  heaters  are  used,  one  is  usually  placed  in  each  square 
formed  by  four  trees  (fig.  9).  A  double  row  is  used  on  the  outside, 
especially  on  the  windward  side.  Storage  facilities  to  handle  fuel  for 
two  or  three  successive  firings  should  be  provided.  For  small  orchards, 
near  an  oil  supply  station,  enough  oil  may  be  secured  from  day  to  day 
and  stored  in  barrels  to  last  for  any  ordinary  cold  period.  For 
orchards  of  ten  acres  or  more  in  size  a  storage  tank  of  2000  to  5000 
gallons,  conveniently  located,  is  essential.  Tested  thermometers  are 
an  absolute  necessity.  It  is  well  to  have  several,  placed  in  different 
parts  of  the  orchard  at  a  uniform  height  from  the  ground.  An 
automatic  electric  frost  alarm  may  be  placed  in  the  coldest  place  in 
the  orchard  and  arranged  to  ring  a  bell  in  the  owner's  sleeping  apart- 
ment when  the  temperature  reaches  the  danger  point.  Tested  ther- 
mometers cost  from  $2  to  $3  each  and  an  electric  frost  alarm  costs 
about  $40  with  wire  extra.  Other  equipment  needed  is  a  supply  of 
covers  for  the  pots  to  exclude  rain  from  the  oil,  a  lighting  torch,  and 
a  tank  wagon  or  handy  truck  holding  several  barrels  to  distribute  the 
oil  to  the  pots'.  A  handy  torch  for  lighting  the  pots  consists  of  an 
oil  can  with  a  long  spout,  such  as  locomotive  engineers  use.  These 
torches  can  be  secured  from  dealers  handling  the  heaters. 

Heaters  are  usually  lighted  when  the  temperature  at  the  coldest 
place  in  the  orchard  (usually  the  lowest  place)  reaches  31°  F.  The  pots 
are  lighted  by  the  flaming  drops  of  gasoline  or  distillate  falling  from 
the  spout  of  the  torch.  An  active  man  should  be  able  to  light  from  200 
to  300  pots  per  hour.  All  of  the  pots  are  seldom  lighted  at  once. 
Usually  the  double  row  on  the  outside  and  several  inside  rows  on  the 
side  of  the  orchard  from  which  the  breeze  is  blowing  are  lighted  first, 
followed  by  alternate  pots  in  the  interior  of  the  orchard  as  quickly 
as  possible.  If  the  temperature  is  not  raised  above  the  danger  point 
in  from  twenty  to  thirty  minutes  the  remainder  of  the  pots  are  started. 
Much  of  the  procedure  covering  these  points  must  be  learned  by  actual 
experience. 

With  the  ordinary  equipment  now  in  use  it  is  comparatively  easy 
to  raise  the  temperature  of  the  air  in  an  orchard  two  or  three  degrees, 
but  very  difficult  to  raise  it  more  than  four  or  five  degrees.  For- 
tunately it  is  rarely  necessary  to  raise  the  temperature  more  than  two 
or  three  degrees  in  most  districts  where  apricots  are  grown.  Frosts 
usually  occur  on  clear,  comparatively  quiet  nights.  The  presence  of 
wind  generally  causes  a  mixing  of  the  stratas  of  air  of  different  tern- 


Circular  238] 


THE   APRICOT   IN    CALIFORNIA 


45 


perature,  preventing  the  settling  of  cold  air  in  the  low  places.  If  frost 
does  occur  when  there  is  a  perceptible  wind,  it  is  much  harder  to 
combat  than  one  on  a  quiet  night.     The  coldest  time  of  the  night  is 


Fig.  9. — One  orchard  heater  per  tree  is  usually  placed  in  the  square  formed 
by  four  trees.  A  double  row  of  heaters  is  placed  next  to  the  outside  row  on  the 
windward  side. 


usually  about  daybreak  or  perhaps  just  before  sunrise,  hence  the 
heaters  must  have  sufficient  capacity  to  burn  until  after  sun-up  if 
necessary.    It  is  easier  to  heat  an  orchard  of  old  spreading  trees  than 


46  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

one  where  the  trees  are  small.  The  top  branches  in  large  trees  have 
often  been  observed  to  produce  fruit  when  the  buds  lower  down  were 
killed  by  frost. 

The  grower  who  is  located  in  a  district  where  orchard  heating  is 
necessary  should  make  a  careful  study  of  conditions  in  his  orchard 
as  regards  air  currents,  cold  places,  and  average  duration  of  frosts  at 
different  stages  of  development  of  the  blossoms  and  young  fruit. 
Much  needless  expense  can  be  saved  by  the  careful  man  who  knows 
when  to  heat  and  when  not  to  heat.  In  the  absence  of  definite  figures 
covering  California  conditions  the  temperatures  which  apricots  are 
likely  to  endure  for  thirty  minutes  or  less  without  being  killed  are  as 
follows:  Buds  closed,  but  showing  color,  27°  to  30°;  in  full  bloom, 
28°  to  31°  ;  after  fruit  has  set,  30°  to  31°.  The  best  complete  treatise 
on  orchard  heating  easily  available  is  Farmers'  Bulletin  No.  1096, 
entitled  "Frost  and  the  Prevention  of  Damage  by  It." 

HAEVESTING  APRICOTS 

For  Canning  Purposes. — Canneries  now  desire  all  fruit  delivered 
to  be  ripe,  though  firm.  This  means  that  the  apricots  must  be  yellow, 
but  may  or  may  not  have  a  blush  on  one  side.  Several  pickings  may 
have  to  be  made  so  that  all  the  fruit  will  be  exactly  in  the  right  con- 
dition. What  has  been  said  applies  to  the  Blenheim  and  Royal.  The 
Tilton  may  be  yellow,  at  least  on  one  side,  and  still  be  too  green  to 
be  harvested  for  canning.  If  in  doubt,  samples  should  be  submitted 
to  the  cannery  before  heavy  picking  begins.  Tolerance  for  overripe 
or  soft  fruit  is  very  small.  If  there  is  more  than  a  mere  sprinkling  of 
overripe  fruit,  the  whole  load  may  be  rejected. 

Canneries  take  but  one  grade  of  fruit,  all  of  which  must  be  above 
a  certain  size.  The  size  specification  varies  from  year  to  year,  accord- 
ing to  market  conditions  and  the  extent  of  the  crop.  One  season  the 
fruit  must  run  twelve  to  the  pound,  while  the  next  fourteens  or  even 
sixteens  may  be  acceptable.  Undersize  fruit  is  dried  or  sold  to  a 
by-products  establishment. 

The  fruit  is  picked  from  the  trees  by  hand.  Each  picker  usually 
carries  a  12-quart  tin  pail  which  he  holds  on  his  arm  or  hangs  on  the 
ladder  by  a  wire  hook.  The  buckets  are  emptied  into  40  or  50-pound 
lug  boxes,  which  are  filled  only  slightly  more  than  level  full  to  prevent 
crushing  when  they  are  stacked  in  the  field  or  in  hauling.  The  cannery 
usually  furnishes  the  lug  boxes,  but  the  grower  may  do  all  the  hauling 
to  and  from  the  cannery  or  to  the  cars.  Competition  among  buyers  or 
other  special  conditions  may  cause  exceptional  arrangements  to  be 
made. 


Circular  238]  THE  APRICOT  IN  CALIFORNIA  47 

The  average  production  is  about  four,  although  exceptional  yields 
as  high  as  eight  tons  have  been  reported. 

For  Drying. — For  drying  purposes  it  is  highly  desirable  that  the 
fruit  be  picked  from  the  trees  rather  than  knocked  off  with  poles,  as 
is  sometimes  done.  Bruised  fruit  does  not  make  a  first-class  dried 
product,  and  is  discriminated  against  under  the  grading  regulations 
of  the  Prune  and  Apricot  Growers'  Association.  The  fruit  should  be 
riper  than  that  preferred  by  canneries,  but  should  be  firm. 

Apricot  cutters,  usually  women  and  girls,  slit  the  fruit  around  the 
suture  or  seam,  remove  the  pit,  and  lay  the  halves  cup-side  up  directly 
on  trays.  The  cutters  sit  at  tables  and  helpers  dump  the  fruit  in  front 
of  them.  Apricot  cutting  is  nearly  always  done  as  piecework,  at  so 
much  per  box.  The  pits  are  tossed  into  a  box  on  the  floor  and  saved, 
as  they  have  considerable  value  for  planting  and  for  by-products 
purposes. 

Assistants  remove  the  trays  as  filled  and  stack  them  on  trucks. 
They  are  then  rolled  into  the  bleaching  house  and  exposed  to  the 
fumes  of  burning  sulphur  for  about  three  hours.  If  the  fruit  is  too 
green,  a  longer  period  of  sulphuring  is  advisable.  When  the  fruit  is 
well  sulphured  the  juice  collects  in  the  "cup,"  which  makes  careful 
handling  of  the  trays  necessary.  After  sulphuring,  the  fruit  should 
be  a  beautiful  golden-yellow.  Sulphuring  shortens  the  drying  period, 
prevents  decomposition,  and  affords  considerable  protection  from 
insects  while  in  storage. 

In  sulphuring,  two  or  three  pounds  of  common  powdered  sulphur 
are  placed  in  a  pit  beneath  one  end  of  the  stack  of  trays  and  lighted 
by  touching  a  match  to  a  handful  of  excelsior  or  a  small  roll  of  paper. 
Eight  to  ten  pounds  of  sulphur  is  allowed  for  each  green  ton  of  fruit. 
The  sulphur  house  is  usually  just  large  enough  to  contain  a  stack  of 
trays  four  to  six  feet  high.  The  house  itself  may  be  constructed  of 
concrete,  brick,  or  wood.  Sulphur  houses  must  be  provided  with 
adjustable  ventilators  at  the  top.  To  be  effective,  the  sulphur  must 
burn  slowly  and  the  fumes  should  circulate  freely. 

In  lieu  of  a  house,  an  inexpensive  sulphuring  device  called  a  hood 
may  be  made  by  constructing  a  framework  of  1  x  4  inch  boards  and 
covering  with  building  paper,  with  numerous  laths  nailed  across  all 
sides  for  the  protection  of  the  paper.  On  either  side,  two  of  the  boards 
should  project  a  foot  or  so  at  both  ends  to  serve  as  handles  for  lifting 
the  hood  over  the  trays  and  off  again  at  the  end  of  the  bleaching  period. 
Earth  may  be  piled  against  the  side  of  the  hood  to  prevent  undue  loss 
of  the  fumes.  The  paper  cover  at  best  will  contain  enough  openings  to 
give  all  needed  ventilation. 


48  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

The  trays  are  exposed  to  the  sun  until  the  fruit  is  nearly  dry.  The 
time  for  drying  varies,  but  is  usually  about  two  days  in  the  sun,  fol- 
lowed by  two  or  three  days  with  the  trays  stacked  in  the  shade.  This 
slow  drying  in  the  shade  gives  the  fruit  a  better  texture.  Apricots  are 
dry  enough  when  they  are  leathery  to  the  touch,  not  hard  nor  brittle. 
Fruit  that  has  become  too  dry  may  be  processed  by  dipping  in  boiling 
water.  It  is  placed  in  a  wire  basket  and  submerged  but  a  few  seconds. 
when  it  may  safely  be  stored  in  bulk  while  wet.  Unless  the  water  is 
boiling  the  fruit  will  mold.  Newly  dried  apricots  may  be  stored  in 
lug  boxes  or  in  bulk  in  bins  until  delivered  to  the  association's  ware- 
house or  to  a  buyer. 

Apricots  dry  at  the  rate  of  about  one  pound  for  each  five  pounds 
of  fresh  fruit.  A  good  yield  would  be  one  and  one-quarter  tons  of 
dried  fruit  per  acre,  although  about  three-quarters  of  a  ton  is  nearer 
the  average. 

For  the  Fresh-fruit  Market. — For  shipment  as  fresh  fruit  to  eastern 
or  other  markets,  apricots  are  harvested  when  they  become  a  light 
yellow,  particularly  if  there  is  a  blush  on  one  side.  The  fruit  is 
carefully  sized,  often  wrapped,  and  packed  in  5-pound  baskets.  Four 
of  these  baskets  make  a  crate.  The  standard  basket  is  approximately 
8  inches  square  at  the  top,  6%  inches  long,  16  inches  wide,  and  4% 
inches  deep,  measured  inside. 

When  packed  in  layers  in  baskets  with  sloping  sides,  the  state  law 
says,  "no  layer  below  the  top  layer  shall  contain  a  greater  numerical 
count  than  the  top  layer."  "When  packed  in  layers  in  containers  with 
straight  lines,  each  layer  must  contain  approximately  the  same  number 
of  fruits.  The  variation  in  size  (except  in  baskets)  "must  not  be  more 
than  one-eighth  of  an  inch  when  measured  through  the  widest  portion 
of  cross  section." 

Generally  speaking,  apricots  when  packed  shall  be  mature,  but  not 
overripe,  well  colored  for  the  variety  and  locality,  virtually  uniform 
in  quality,  practically  free  from  insect  and  fungus  pests,  rot,  bruises, 
frost  injury,  sunburn,  and  other  serious  defects,  and  virtually  uniform 
in  size. 

The  chief  early  apricot  districts  of  the  state  are  in  the  vicinity  of 
Vacaville,  Solano  County,  especially  Vaca  Valley  and  Pleasant  Valley, 
and  the  nearby  Winters  and  Guinda  districts  in  Yolo  County.  Another 
increasingly  important  early  district  is  the  Imperial  Valley.  Heavy 
shipments  of  early  apricots  formerly  went  east  from  the  Newcastle 
section  of  Placer  County,  but  the  plantings  there  are  being  rapidly 
replaced  by  plnms  and  peaches. 


Circular  238]  THe  apricot  in  California  49 

The  Newcastle  is  the  favorite  variety  of  apricot  for  early  shipment, 
but  the  Royal  and  even  the  Blenheim  are  also  shipped  to  a  considerable 
extent,  especially  from  the  Imperial  Valley. 

VAEIETIES  OF  APRICOTS 

The  chief  variety  of  apricot  for  drying  purposes  has  been  the 
Royal,  for  canning  the  Blenheim,  and  for  early  shipment  to  fresh  fruit 
markets  the  Newcastle  Early.  In  especially  early  or  late  locations, 
other  varieties  may  be  shipped  fresh.  In  like  manner,  all  varieties 
may  be  dried  and  others,  especially  the  Royal  and  Tilton,  in  addition 
to  the  Blenheim,  be  sold  for  canning. 

In  1920  the  California  State  Department  of  Agriculture  called  a 
conference  for  the  purpose  of  standardizing  fruit  varieties  for  plant- 
ing. Representatives  from  various  interests  were  present,  including 
growers,  nurserymen,  canners,  shippers,  and  officers  of  dried  and  green 
fruit  associations.  An  effort  was  made  to  eliminate  useless  varieties 
by  recommending  that  their  further  propagation  be  discontinued. 

The  following  apricots  were  recommended  for  planting: 

For  the  Coast :  Blenheim,  100  per  cent  for  canning.  Could  also  be 
used  for  drying. 

For  the  San  Joaquin  Valley  :  Tilton,  100  per  cent  for  drying.  Could 
also  be  used  for  canning. 

For  the  Sacramento  Valley :  Tilton,  50  per  cent ;  Blenheim,  50  per 
cent;  for  drying  or  canning. 

The  Royal  was  recommended  as  a  commercial  variety,  but  for  what 
purpose  or  locality  was  not  stated.  However,  it  was  understood  that 
it  might  be  replaced  by  the  Blenheim  and  Tilton,  which,  it  was  thought, 
would  answer  all  purposes  heretofore  served  by  the  Royal. 

The  planting  of  Moorpark  was  recommended  for  drying  purposes 
only,  without  mentioning  localities. 

Routier's  Peach  and  Hemskirke  were  recommended  only  as  home 
orchard  varieties. 

Royal. — A  French  variety  which  for  years  was  the  leader  in  the 
state  in  point  of  acreage  planted.  The  Royal  has  been  our  chief  drying 
variety.  It  is  also  excellent  for  canning ;  of  a  large  size  when  properly 
thinned,  dull  yellow  in  color  with  orange  cheeks,  free  stone,  fine  flavor, 
good  bearer,  fruit  ripening  evenly  when  trees  are  properly  opened  up 
by  pruning ;  fruit  roundish,  medium  to  large,  oval,  slightly  compressed 
and  with  a  shallow  suture ;  flesh  pale  orange,  firm  and  juicy,  and  with 
a  rich  flavor  when  fully  ripe.  The  time  of  ripening  at  the  University 
Farm,  Davis,  in  the  Sacramento  Valley,  has  been  from  the  10th  to  the 


50  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

20th  of  July.  In  the  Imperial  Valley  it  may  ripen  nearly  a  month 
earlier. 

Blenheim  is  now  first  in  popularity  for  all  purposes;  the  leading 
canning  variety  in  the  coastal  region ;  so  nearly  like  the  Royal  that 
growers  of  wide  experience  cannot  tell  the  two  varieties  apart ;  a 
vigorous  grower,  and  on  the  coast  a  regular  and  prolific  bearer; 
reputed  to  be  later  in  ripening  than  the  Royal,  but  at  Davis  the  two 
are  ready  to  harvest  at  almost  the  same  time.  Grown  for  canning, 
the  fruit  must  be  heavily  thinned  to  secure  proper  size.  Fruit  similar 
in  all  respects  to  the  Royal.  A  shy  bearer  at  Davis,  but  a  heavy 
producer  in  the  San  Francisco  Bay  region  and  in  all  the  coastal  valleys 
to  the  southward,  and  also  in  Riverside  County.  Very  susceptible  to 
brown  rot  throughout  the  coastal  region. 

Tilton  is  now  next  in  popularity  to  the  Blenheim ;  growTn  chiefly  in 
the  interior  valley  sections ;  often  blooms  two  weeks  later  than  the 
Royal  or  Blenheim,  which  gives  it  considerable  protection  from  frost. 
So  far,  the  Tilton  has  been  almost  entirely  free  from  attack  by 
brown  rot,  because  no  doubt  of  its  late  blooming  habit.  At  Davis,  the 
Tilton  ripens  fully  a  week  later  than  the  Royal  or  Blenheim.  The 
trees  are  strong,  healthy  growers,  and  excellent  producers.  At  Davis 
trees  now  fourteen  years  old  have  increased  steadily  in  yield  for  the 
past  six  years,  under  the  long  system  of  pruning,  and  so  far,  the  tops 
have  not  had  to  be  reduced  by  cutting  to  laterals  to  induce  new  twig 
growth. 

Wickson  says  the  Tilton  was  originated  by  J.  E.  Tilton  near  Han- 
ford,  Kings  County,  about  1885  from  a  chance  seedling.  The  fruit  is 
large,  symmetrical,  and  has  a  free  stone.  The  flesh  has  a  fine  yellow 
color  that  makes  it  acceptable  for  both  drying  and  canning.  The  chief 
drawback  to  the  Tilton  is  its  habit  of  coloring  before  it  is  ripe.  If 
judged  by  the  usual  standards,  it  is  apt  to  be  taken  to  the  cannery  too 
green.  This  is  doubtless  the  reason  canners  discriminate  against  it  in 
some  quarters.  The  Tilton  is  rapidly  becoming  the  favorite  for  all 
purposes  in  the  Sacramento  and  San  Joaquin  valleys. 

Moorpark. — This  is  an  old  English  variety  which  is  excellent  for 
drying.  The  trees  are  unusually  large  and  generally  very  robust  in 
point  of  vigor.  The  fruit  is  larger  than  the  Royal,  Blenheim,  or 
Tilton,  and  of  very  fine  flavor,  which  makes  it  a  superior  variety  for 
eating  purposes.  However,  it  ripens  too  late  to  find  a  place  in  the 
trade.  The  Moorpark  as  a  tree  appears  to  thrive  wherever  apricots 
can  be  grown,  but  seems  to  do  especially  well  in  the  cool  coastal  valleys. 
It  has  the  reputation  of  being  a  shy  bearer,  but  where  light  pruning 
with  no  heading  back  is  practiced,  it  usually  produces  well.     In  sec- 


Circular  238]  the  apricot  in  CALIFORNIA  51 

tions  where  the  Blenheim  is  grown  almost  exclusively,  the  canneries 
will  usually  not  take  the  Moorpark,  for  the  reason  that  they  do  not 
care  to  mix  varieties.  The  Moorpark  is  very  profitable  for  drying 
when  the  trees  bear  regularly.  Nearly  all  the  fruit  makes  a  fancy 
dried  product  which  is  readily  accepted  under  the  grading  rules  of 
the  Prune  and  Apricot  Growers'  Association. 

Hemskirke. — A  shy  bearer  in  many  places,  and  recommended  only 
for  planting  in  home  orchards.  The  fruit  is  described  as  "large, 
roundish,  but  considerably  compressed  or  flattened ;  skin  orange,  with 
red  cheeks ;  flesh  bright  orange,  tender,  rather  more  juicy  and  sprightly 
than  Moorpark,  with  rich,  luscious,  plum-like  flavor;  stone  not  per- 
forate, rather  small,  and  kernel  bitter."  The  quality  for  eating  pur- 
poses when  fresh  makes  it  a  desirable  addition  to  the  home  fruit  tree 
collection. 

Newcastle. — "Originated  with  C.  M.  Silva  &  Sons,  Newcastle, 
Placer  County,  in  1881.  Size  medium,  round,  with  spherical  pit ;  free 
stone;  not  quite  so  large  as  the  Royal  nor  quite  so  rich  in  flavor,  but 
more  highly  colored ;  rather  darker  on  the  sunny  side.  Early,  regular 
and  good  bearer,  a  medium  grower,  more  upright  than  the  Royal." 
Ripens  three  to  four  weeks  earlier  than  the  Royal  at  Davis,  in  the 
Sacramento  Valley.  This  is  the  chief  variety  shipped  to  the  early 
eastern  markets.  It  is  grown  chiefly  in  the  Coast  Range  foothills  and 
valleys,  particularly  in  the  vicinity  of  Vacaville.  Ripens  in  the 
Imperial  Valley  as  early  as  April  or  the  first  part  of  May. 

COST  OF  GROWING  APRICOTS 
The  cost  of  growing  apricots  cannot  be  stated  definitely.  Owing  to 
increased  cost  of  labor  and  materials  during  the  past  few  years,  the 
cost  has  been  greater  than  during  the  pre-war  period.  At  the  present 
time,  prices  are  being  reduced,  but  whether  or  not  the  pre-war  level 
will  be  reached  cannot  be  predicted.  In  attempting  to  arrive  at  a 
conservative  estimate  of  costs,  the  Division  of  Farm  Management  at 
the  University  of  California  has  compiled  considerable  data.  The  costs 
given  represent  averages  based  on  pre-war  conditions,  with  such  figures 
on  present  prices  as  are  available  at  this  time. 

Value  of  Land: 

Raw  Land : 

High  (with  water)  $400.00  per  acre 

Low  (with  water)  150.00  per  acre 

Usual  (with  water)  200.00  per  acre 

Developed  Orchards: 

High-producing $1,200.00  per  acre 

Usual  producing 800.00  per  acre 


52  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


In  the  San  Francisco  Bay  region,  including  the  Santa  Clara  Valley, 
all  values  will  range  about  50  per  cent  higher  than  the  figures  given 
above. 

Cost  of  Establishing  Orchards: 

(Irrigation  system  or  water  right  included  in  price  of  land). 
Clearing,   grading  and   leveling  land   for 

planting  ($10  to  $75) $20.00  per  acre 

Trees  (at  20c,  price  in  1920  much  higher, 

50c  up) - 15.00  per  acre 

Setting  out  ($4  to  $8)  _ 5.00  per  acre 

Replanting 1.50  per  acre 

These  costs  are  subject  to  extreme  variation,  depending  upon  the 
topography  of  the  land  and  the  prevailing  scale  for  man  and  horse  or 
tractor  work.  Owing  to  greatly  increased  demand,  the  price  of  nursery 
trees  has  been  much  higher  during  the  past  two  or  three  years  than 
formerly. 

The  annual  cost  from  setting  out  to  self-sustaining  age  is  given 
approximately  as  follows : 

Cultivating $6.00  per  acre 

Irrigating  ($2  to  $12)  6.00  per  acre 

Pruning 3.00  per  acre 

As  intercrops  are  usually  grown  in  young  orchards,  the  expense 
of  cultivating  and  irrigating  is,  as  a  rule,  borne  by  the  intercrop.  No 
data  are  available  on  the  cost  of  these  operations  at  the  present  time. 

The  diversity  in  the  actual  operation  connected  with  a  mature 
orchard,  together  with  the  average  grower 's  disinclination  to  keep  cost 
figures,  renders  it  difficult  to  give  a  statement  of  costs  that  will  be 
suitable  for  all  conditions.  The  comparatively  high  cost  of  many  of 
the  necessary  orchard  operations  is  due  to  the  high  wages  that  have 
prevailed  during  recent  years.  At  the  present  time,  the  wages  being 
paid  are  somewhat  less  than  during  the  war  period,  but  not  so  low 
as  before  that  period.  Cultivation  costs  vary  from  $8  to  as  high  as 
$20  per  acre.  Pruning,  which  before  the  war  cost  about  $12  per  acre, 
now  costs  from  $30  to  $35  per  acre.  For  the  past  season,  the  rate  of 
50  cents  per  tree  was  quite  common  in  mature  orchards.  For  irrigation 
the  cost  varies  so  greatly  in  different  districts  that  no  general  figures 
can  be  given.  The  costs  vary  from  a  nominal  price  in  some  sections 
where  water  is  supplied  by  gravity  to  as  high  as  $30  to  $35  per  acre 
per  application,  when  water  must  be  lifted  from  great  depths.  Spray- 
ing costs  about  $15  per  acre  per  application.     Considerable  contract 


Circular  238]  the  apricot  IN  CALIFORNIA  53 

spraying  at  the  rate  of  3y2  cents  per  gallon  was  done  the  past  season 
in  some  districts.  When  more  than  one  spraying  is  necessary,  the 
cost  is  proportionally  greater.  Thinning  cost  from  $5  to  $15  per  acre, 
according  to  the  size  of  the  trees  and  the  amount  of  fruit  set.  Digging 
out  borers,  probably  cost  from  $3  to  $5  per  acre.  In  addition  to  the 
preceding  expenses,  it  is  necessary  to  heat  some  orchards  to  prevent 
damage  by  frost.  This  involves  an  additional  expense  for  pots,  storage 
tanks,  and  the  necessary  thermometers.  The  cost  for  oil  in  1921  varied 
from  $8  to  $20  per  acre,  according  to  the  number  of  times  it  was 
necessary  to  light  the  heaters. 

The  average  cost  of  picking  apricots  in  the  last  year  or  two  ranged 
from  $10  to  $15  per  ton  of  green  fruit,  whereas  the  price  was  formerly 
from  $3  to  $6.  "When  the  fruit  is  to  be  dried,  about  two  cutters  are 
needed  for  each  picker.  The  scale  for  cutting  is  approximately  from 
10  cents  to  12  cents  per  box.  From  statistics  collected  in  1916  the 
estimated  cost  of  drying  apricots  was  $35  to  $50  per  dry  ton.  Esti- 
mates for  the  same  operation  in  1920  indicate  that  $90  to  $100  would 
more  nearly  approximate  the  cost.  Convenience  of  arrangement  in  the 
dry  yard  and  accessibility  to  the  packing  house  very  materially  affect 
these  items.  As  previously  stated,  the  cost  of  these  various  operations 
in  1921  will  undoubtedly  be  reduced. 

For  drying,  more  equipment  is  needed  than  where  the  fruit  is  sold 
to  the  cannery.  This  equipment  consists  in  cutting  sheds  with  suitable 
tables  and  benches,  sulphur  houses,  lug  boxes,  and  trays.  The  cutting 
sheds  are  usually  inexpensive  frame  structures,  open  on  all  four  sides, 
and  are  used  for  storing  trays  or  machinery  during  the  winter.  The 
sulphur  houses  are  constructed  either  of  wood  or  concrete.  The  latter 
are  more  permanent  than  the  former,  but  cost  more  to  construct.  For 
a  crop  of  50  green  tons,  a  minimum  of  300  lug  boxes  are  necessary. 
About  800  to  1200  trays  of  the  3x8  foot  size  are  ordinarily  required 
for  a  50-ton  crop.  Apricots  do  require  so  long  a  time  to  dry  as  prunes, 
but  the  harvesting  season  is  shorter.  The  trays  are  used  two,  three,  or 
possibly  more  times  a  season,  depending  upon  the  rate  of  drying.  The 
cost  of  the  3x8  foot  trays  is  about  80  cents  to  90  cents  a  piece.  Lug 
boxes  cost  from  20  cents  to  30  cents  a  piece. 

The  foregoing  items  include  only  the  cost  of  land  and  labor  in 
bringing  an  orchard  into  bearing  and  harvesting  the  crop.  Equipment, 
such  as  plows,  harrows,  cultivators,  pruning  tools,  and  a  sprayer  must 
also  be  provided.  The  interest  and  depreciation  on  these  implements, 
as  well  as  the  depreciation  on  buildings,  the  taxes  and  insurance,  and 
the  interest  on  the  investment  must  all  be  considered  in  arriving  at 
the  cost  of  production. 


STATION  PUBLICATIONS  AVAILABLE  FOR  FREE  DISTRIBUTION 


BULLETINS 


No. 
185. 

241. 
246. 
251. 

253. 

261. 
262. 

263. 
266. 

267. 
268. 
270. 


271. 
273. 

275. 

276. 
278. 
279. 
280. 

282. 

283. 
285. 
286. 
287. 
294. 
297. 
298. 
299. 


No. 

Report  of  Progress  in  Cereal  Investiga-  300. 

tions.  304. 
Vine  Pruning  in  California,  Part  I. 

Vine  Pruning  in  California,  Part  II.  308. 
Utilization  of  the  Nitrogen  and  Organic 

Matter    in    Septic    and    Imhoff    Tank 

Sludges.  309. 
Irrigation    and    Soil    Conditions    in    the 

Sierra  Nevada  Foothills,  California.  310. 

Melaxuma  of  the  Walnut,  "Juglans  regia."  312. 

Citrus    Diseases    of    Florida    and    Cuba  313. 

Compared  with  Those  of  California.  316. 

Size  Grades  for  Ripe  Olives.  317. 

A  Spotting  of  Citrus  Fruits  Due  to  the  318. 

Action  of  Oil  Liberated  from  the  Rind.  320. 
Experiments  with  Stocks  for  Citrus.  321. 
Growing  and  Grafting  Olive  Seedlings.  323. 
A  Comparison  of  Annual  Cropping,  Bi- 
ennial   Cropping,    and    Green    Manures  324. 

on  the  Yield  of  Wheat. 

Feeding  Dairy  Calves  in  California.  325. 
Preliminary  Report  on  Kearney  Vineyard 

Experimental  Drain. 

The  Cultivation  of  Belladonna  in  Cali-  328. 

fornia.  330. 

The  Pomegranate.  331. 

Grain  Sorghums.  332. 

Irrigation  of  Rice  in  California.  334. 
Irrigation  of  Alfalfa  in  the  Sacramento 

Valley.  335. 
Trials  with   California   Silage   Crops   for 

Dairy  Cows.  336. 
The  Olive  Insects  of  California. 

The  Milk  Goat  in  California.  337. 

Commercial  Fertilizers.  339. 
Vinegar  from  Waste  Fruits. 

Bean  Culture  in  California.  340. 

The  Almond  in  California.  341. 

Seedless  Raisin  Grapes.  342. 
The  Use  of  Lumber  on  California  Farms. 


Commercial  Fertilizers. 

A  Study  on  the  Effects  of  Freezes  on 
Citrus  in  California. 

I.  Fumigation  with  Liquid  Hydrocyanic 
Acid.  II.  Physical  and  Chemical  Pro- 
perties of  Liquid  Hydrocyanic  Acid. 

I.  The  Carob  in  California.  II.  Nutritive 
Value  of  the  Carob  Bean. 

Plum  Pollination. 

Mariout  Barley. 

Pruning  Young  Deciduous  Fruit  Trees. 

The  Kaki  or  Oriental  Persimmon. 

Selections  of  Stocks  in  Citrus  Propagation. 

The  Effects  of  Alkali  on  Citrus  Trees. 

Control  of  the  Coyote  in  California. 

Commercial  Production  of  Grape  Syrup. 

Heavy  vs.  Light  Grain  Feeding  for  Dairy 
Cows. 

Storage  of  Perishable  Fruit  at  Freezing 
Temperatures. 

Rice  Irrigation  Measurements  and  Ex- 
periments in  Sacramento  Valley,  1914- 
1919. 

Prune  Growing  in  California. 

Dehydration  of  Fruits. 

Phylloxera-Resistant  Stocks. 

Walnut  Culture  in  California. 

Preliminary  Volume  Tables  for  Second- 
Growth  Redwoods. 

Cocoanut  Meal  as  a  Feed  for  Dairy  Cows 
and  Other  Livestock. 

The  Preparation  of  Nicotine  Dust  as  an 
Insecticide. 

Some  Factors  of  Dehydrater  Efficiency. 

The  Relative  Cost  of  Making  Logs  from 
Small  and  Large  Timber. 

Control  of  the  Pocket  Gopher  in  California. 

Studies  on  Irrigation  of  Citrus  Groves. 

Hog  Feeding  Experiments. 


CIRCULAES 


No.  No. 

70.  Observations    on    the    Status    of    Corn  164. 

Growing  in  California.  165. 

82.  The  Common  Ground  Squirrels  of  Cali- 
fornia. 166. 

87.  Alfalfa.  167. 

110.  Green  Manuring  in  California.  169. 

111.  The  Use  of  Lime  and  Gypsum  on  Cali-  170. 

fornia  Soils. 

113.  Correspondence  Courses  in  Agriculture.  172. 

115.  Grafting  Vinif era  Vineyards.  173. 

126.  Spraying  for  the  Grape  Leaf  Hopper.  174. 

127.  House  Fumigation.  175. 

128.  Insecticide  Formulas. 

129.  The  Control  of  Citrus  Insects.  178. 

130.  Cabbage  Growing  in  California.  179. 
138.  The  Silo  in  California  Agriculture. 

144.  Oidium  or  Powdery  Mildew  of  the  Vine.  181. 

148.  "Lungworms."  182. 

151.  Feeding  and  Management  of  Hogs. 

152.  Some  Observations  on  the  Bulk  Handling  183. 

of  Grain  in  California.  184. 

153.  Announcement    of   the    California    State  188. 

Dairy  Cow  Competition,  1916-18.  189. 

154.  Irrigation    Practice    in    Growing    Small  190. 

Fruits  in  California.  193. 

155.  Bovine  Tuberculosis.  198. 

157.  Control  of  the  Pear  Scab.  201. 

158.  Home  and  Farm  Canning.  202. 

159.  Agriculture  in  the  Imperial  Valley. 

160.  Lettuce  Growing  in  California.  203. 

161.  Potatoes  in  California.  205. 


Small  Fruit  Culture  in  California. 

Fundamentals  of  Sugar  Beet  Culture 
under  California  Conditions. 

The  County  Farm  Bureau. 

Feeding  Stuffs  of  Minor  Importance. 

The  1918  Grain  Crop. 

Fertilizing  California  Soils  for  the  1918 
Crop. 

Wheat  Culture. 

The  Construction  of  the  Wood-Hoop  Silo. 

Farm  Drainage  Methods. 

Progress  Report  on  the  Marketing  and 
Distribution  of  Milk. 

The  Packing  of  Apples  in  California. 

Factors  of  Importance  in  Producing  Milk 
of  Low  Bacterial  Count. 

Control  of  the  California  Ground  Squirrel. 

Extending  the  Area  of  Irrigated  Wheat  in 
California  for  1918. 

Infectious  Abortion  in  Cows. 

A  Flock  of  Sheep  on  the  Farm. 

Lambing  Sheds. 

Winter  Forage  Crops. 

Agriculture  Clubs  in  California. 

A  Study  of  Farm  Labor  in  California. 

Syr-ip  from  Sweet  Sorghum. 

Helpful  Hints  to  Hog  Raisers. 

County  Organizations  for  Rural  Fire  Con- 
trol 

Peat  is  a  Manure  Substitute. 

Blackleg. 


CIRCULARS — Continued 


No.  No. 

206.  Jack  Chee§e.  231. 

208.  Summary  of  the  Annual  Reports  of  the  232. 

Farm  Advisors  of  California. 
The  Function  of  the  Farm  Bureau.  233. 

Suggestions  to  the  Settler  in  California.  234. 

Salvaging  Rain-Damaged  Prunes. 
Seed    Treatment    for    the    Prevention    of  235. 

Cereal  Smuts. 
Feeding  Dairy  Cows  in  California.  236. 

Methods    for    Marketing    Vegetables    in 

California. 
Advanced  Registry  Testing  of  Dairy  Cows.  237. 

The  Present  Status  of  Alkali. 

Unfermented  Fruit  Juices.  238. 

How  California  is  Helping  People  Ow  n  238. 

Farms  and  Rural  Homes.  239. 

The  Pear  Thrips. 
Control  of  the  Brown  Apricot  Scale  and  240. 

the    Italian   Pear   Scale    on    Deciduous 

Fruit  Trees.  .  241. 

225.  Propagation  of  Vines. 

227.  Plant  Diseases  and  Pest  Control.  242. 

228.  Vineyard  Irrigation  in  Arid  Climates.  243. 

229.  Cordon  Pruning. 

230.  Testing  Milk,  Cream,  and  Skim  Milk  for  244. 

Butterfat.  245. 


209 
210 
212 
214 

215 
217 

218 
219 
220 
221 

223 

224 


The  Home  Vineyard. 

Harvesting  and  Handling  California 
Cherries  for  Eastern  Shipment. 

Artificial  Incubation. 

Winter  Injury  to  Young  Walnut  Trees 
During  1921-22. 

Soil  Analysis  and  Soil  and  Plant  Inter- 
relations. 

The  Common  Hawks  and  Owls  of  Cali- 
fornia from  the  Standpoint  of  the 
Rancher. 

Directions  for  the  Tanning  and  Dressing 
of  Furs. 

The  Apricot  in  California. 

The  Apricot  in  California. 

Harvesting  and  Handling  Apricots  and 
Plums  for  Eastern  Shipment. 

Harvesting  and  Handling  Pears  for  East- 
ern Shipment. 

Harvesting  and  Handling  Peaches  for 
Eastern  Shipment. 

Poultry  Feeding. 

Marmalade  Juice  and  Jelly  Juice  from 
Citrus  Fruits. 

Central  Wire  Bracing  for  Fruit  Trees. 

Vine  Pruning  Systems. 


